diff --git a/components/script/dom/characterdata.rs b/components/script/dom/characterdata.rs
index be4fc4d0ac1..9db34a49f8c 100644
--- a/components/script/dom/characterdata.rs
+++ b/components/script/dom/characterdata.rs
@@ -6,6 +6,7 @@
 
 use dom::bindings::cell::DOMRefCell;
 use dom::bindings::codegen::Bindings::CharacterDataBinding::CharacterDataMethods;
+use dom::bindings::codegen::Bindings::NodeBinding::NodeBinding::NodeMethods;
 use dom::bindings::codegen::Bindings::ProcessingInstructionBinding::ProcessingInstructionMethods;
 use dom::bindings::codegen::InheritTypes::{CharacterDataTypeId, NodeTypeId};
 use dom::bindings::codegen::UnionTypes::NodeOrString;
@@ -16,9 +17,10 @@ use dom::bindings::str::DOMString;
 use dom::comment::Comment;
 use dom::document::Document;
 use dom::element::Element;
-use dom::node::{Node, NodeDamage};
+use dom::node::{ChildrenMutation, Node, NodeDamage};
 use dom::processinginstruction::ProcessingInstruction;
 use dom::text::Text;
+use dom::virtualmethods::vtable_for;
 use dom_struct::dom_struct;
 use servo_config::opts;
 use std::cell::Ref;
@@ -85,6 +87,16 @@ impl CharacterDataMethods for CharacterData {
         self.content_changed();
         let node = self.upcast::<Node>();
         node.ranges().replace_code_units(node, 0, old_length, new_length);
+
+        // If this is a Text node, we might need to re-parse (say, if our parent
+        // is a <style> element.) We don't need to if this is a Comment or
+        // ProcessingInstruction.
+        if let Some(_) = self.downcast::<Text>() {
+            if let Some(parent_node) = node.GetParentNode() {
+                let mutation = ChildrenMutation::ChangeText;
+                vtable_for(&parent_node).children_changed(&mutation);
+            }
+        }
     }
 
     // https://dom.spec.whatwg.org/#dom-characterdata-length
diff --git a/components/script/dom/node.rs b/components/script/dom/node.rs
index bf24682ede7..333b47c3a2c 100644
--- a/components/script/dom/node.rs
+++ b/components/script/dom/node.rs
@@ -2490,6 +2490,11 @@ pub enum ChildrenMutation<'a> {
         next: Option<&'a Node>,
     },
     ReplaceAll { removed: &'a [&'a Node], added: &'a [&'a Node] },
+    /// Mutation for when a Text node's data is modified.
+    /// This doesn't change the structure of the list, which is what the other
+    /// variants' fields are stored for at the moment, so this can just have no
+    /// fields.
+    ChangeText,
 }
 
 impl<'a> ChildrenMutation<'a> {
@@ -2541,6 +2546,9 @@ impl<'a> ChildrenMutation<'a> {
     }
 
     /// Get the child that follows the added or removed children.
+    /// Currently only used when this mutation might force us to
+    /// restyle later children (see HAS_SLOW_SELECTOR_LATER_SIBLINGS and
+    /// Element's implementation of VirtualMethods::children_changed).
     pub fn next_child(&self) -> Option<&Node> {
         match *self {
             ChildrenMutation::Append { .. } => None,
@@ -2548,6 +2556,7 @@ impl<'a> ChildrenMutation<'a> {
             ChildrenMutation::Prepend { next, .. } => Some(next),
             ChildrenMutation::Replace { next, .. } => next,
             ChildrenMutation::ReplaceAll { .. } => None,
+            ChildrenMutation::ChangeText => None,
         }
     }
 
@@ -2585,6 +2594,7 @@ impl<'a> ChildrenMutation<'a> {
 
             ChildrenMutation::Replace { prev: None, next: None, .. } => unreachable!(),
             ChildrenMutation::ReplaceAll { .. } => None,
+            ChildrenMutation::ChangeText => None,
         }
     }
 }
diff --git a/components/script/dom/nodelist.rs b/components/script/dom/nodelist.rs
index 31e4dfb40c8..c639b3fa4e9 100644
--- a/components/script/dom/nodelist.rs
+++ b/components/script/dom/nodelist.rs
@@ -279,6 +279,7 @@ impl ChildrenList {
                     self.last_index.set(middle as u32);
                 }
             },
+            ChildrenMutation::ChangeText => {},
         }
     }
 
diff --git a/tests/wpt/metadata-css/css-variables-1_dev/html/test_variable_legal_values.htm.ini b/tests/wpt/metadata-css/css-variables-1_dev/html/test_variable_legal_values.htm.ini
deleted file mode 100644
index f99869b61c6..00000000000
--- a/tests/wpt/metadata-css/css-variables-1_dev/html/test_variable_legal_values.htm.ini
+++ /dev/null
@@ -1,71 +0,0 @@
-[test_variable_legal_values.htm]
-  type: testharness
-  [percentage]
-    expected: FAIL
-
-  [number]
-    expected: FAIL
-
-  [length]
-    expected: FAIL
-
-  [time]
-    expected: FAIL
-
-  [function]
-    expected: FAIL
-
-  [nested_function]
-    expected: FAIL
-
-  [parentheses]
-    expected: FAIL
-
-  [braces]
-    expected: FAIL
-
-  [brackets]
-    expected: FAIL
-
-  [at_keyword_unknown]
-    expected: FAIL
-
-  [at_keyword_known]
-    expected: FAIL
-
-  [at_keyword_unknown_and_block]
-    expected: FAIL
-
-  [at_keyword_known_and_block]
-    expected: FAIL
-
-  [unbalanced_close_bracket_at_toplevel]
-    expected: FAIL
-
-  [unbalanced_close_paren_at_toplevel]
-    expected: FAIL
-
-  [unbalanced_close_bracket_in_something_balanced]
-    expected: FAIL
-
-  [unbalanced_close_paren_in_something_balanced]
-    expected: FAIL
-
-  [unbalanced_close_brace_in_something_balanced]
-    expected: FAIL
-
-  [CDO_at_top_level]
-    expected: FAIL
-
-  [CDC_at_top_level]
-    expected: FAIL
-
-  [semicolon_not_at_top_level_value_unused]
-    expected: FAIL
-
-  [CDO_not_at_top_level_value_unused]
-    expected: FAIL
-
-  [CDC_not_at_top_level_value_unused]
-    expected: FAIL
-
diff --git a/tests/wpt/metadata-css/cssom-1_dev/html/selectorSerialize.htm.ini b/tests/wpt/metadata-css/cssom-1_dev/html/selectorSerialize.htm.ini
index a8ae948e2cf..2796fc6ff28 100644
--- a/tests/wpt/metadata-css/cssom-1_dev/html/selectorSerialize.htm.ini
+++ b/tests/wpt/metadata-css/cssom-1_dev/html/selectorSerialize.htm.ini
@@ -3,24 +3,6 @@
   [:nth-child serialization produces canonical form]
     expected: FAIL
 
-  [single universal selector shows '*' when serialized.]
-    expected: FAIL
-
-  [single type (simple) selector in the sequence of simple selectors that is not a universal selector]
-    expected: FAIL
-
-  [single class (simple) selector in the sequence of simple selectors that is not a universal selector]
-    expected: FAIL
-
-  [single id (simple) selector in the sequence of simple selectors that is not a universal selector]
-    expected: FAIL
-
-  [single pseudo (simple) selector which does not accept arguments in the sequence of simple selectors that is not a universal selector]
-    expected: FAIL
-
-  [single pseudo (simple) selector "lang" which accepts arguments in the sequence of simple selectors that is not a universal selector]
-    expected: FAIL
-
   [single pseudo (simple) selector "nth-child" which accepts arguments in the sequence of simple selectors that is not a universal selector]
     expected: FAIL
 
@@ -32,7 +14,3 @@
 
   [single pseudo (simple) selector ":nth-last-of-type" which accepts arguments in the sequence of simple selectors that is not a universal selector]
     expected: FAIL
-
-  [single pseudo (simple) selector ":not" which accepts arguments in the sequence of simple selectors that is not a universal selector]
-    expected: FAIL
-
diff --git a/tests/wpt/metadata-css/cssom-1_dev/html/serialize-namespaced-type-selectors.htm.ini b/tests/wpt/metadata-css/cssom-1_dev/html/serialize-namespaced-type-selectors.htm.ini
index 74b251714bc..9f40c3d2635 100644
--- a/tests/wpt/metadata-css/cssom-1_dev/html/serialize-namespaced-type-selectors.htm.ini
+++ b/tests/wpt/metadata-css/cssom-1_dev/html/serialize-namespaced-type-selectors.htm.ini
@@ -1,59 +1,11 @@
 [serialize-namespaced-type-selectors.htm]
   type: testharness
-  [Simple type selector]
-    expected: FAIL
-
-  [Type selector without a namespace]
-    expected: FAIL
-
   [Type selector with any namespace]
     expected: FAIL
 
-  [Universal selector]
-    expected: FAIL
-
-  [Universal selector without a namespace]
-    expected: FAIL
-
   [Universal selector in any namespace]
     expected: FAIL
 
-  [Type selector with namespace]
-    expected: FAIL
-
-  [Universal selector with namespace]
-    expected: FAIL
-
-  [Simple type selector followed by class]
-    expected: FAIL
-
-  [Simple type selector followed by id]
-    expected: FAIL
-
-  [Simple type selector followed by pseudo class]
-    expected: FAIL
-
-  [Simple type selector followed by pseudo element]
-    expected: FAIL
-
-  [Simple type selector followed by atttribute selector]
-    expected: FAIL
-
-  [Type selector without a namespace followed by class]
-    expected: FAIL
-
-  [Type selector without a namespace followed by id]
-    expected: FAIL
-
-  [Type selector without a namespace followed by pseudo class]
-    expected: FAIL
-
-  [Type selector without a namespace followed by pseudo element]
-    expected: FAIL
-
-  [Type selector without a namespace followed by attribute selector]
-    expected: FAIL
-
   [Type selector with any namespace followed by class]
     expected: FAIL
 
@@ -84,21 +36,6 @@
   [Universal selector followed by attribute selector]
     expected: FAIL
 
-  [Universal selector without a namespace followed by class]
-    expected: FAIL
-
-  [Universal selector without a namespace followed by id]
-    expected: FAIL
-
-  [Universal selector without a namespace followed by pseudo class]
-    expected: FAIL
-
-  [Universal selector without a namespace followed by pseudo element]
-    expected: FAIL
-
-  [Universal selector without a namespace followed by attribute selector]
-    expected: FAIL
-
   [Universal selector in any namespace followed by class]
     expected: FAIL
 
@@ -114,36 +51,6 @@
   [Universal selector in any namespace followed by attribute selector]
     expected: FAIL
 
-  [Type selector with namespace followed by class]
-    expected: FAIL
-
-  [Type selector with namespace followed by id]
-    expected: FAIL
-
-  [Type selector with namespace followed by pseudo class]
-    expected: FAIL
-
-  [Type selector with namespace followed by pseudo element]
-    expected: FAIL
-
-  [Type selector with namespace followed by attribute selector]
-    expected: FAIL
-
-  [Universal selector with namespace followed by class]
-    expected: FAIL
-
-  [Universal selector with namespace followed by id]
-    expected: FAIL
-
-  [Universal selector with namespace followed by pseudo class]
-    expected: FAIL
-
-  [Universal selector with namespace followed by pseudo element]
-    expected: FAIL
-
-  [Universal selector with namespace followed by attribute selector]
-    expected: FAIL
-
   [Type selector with namespace equal to default namespace]
     expected: FAIL
 
diff --git a/tests/wpt/metadata/cssom/selectorSerialize.html.ini b/tests/wpt/metadata/cssom/selectorSerialize.html.ini
index d92a9d29317..816fb7d846d 100644
--- a/tests/wpt/metadata/cssom/selectorSerialize.html.ini
+++ b/tests/wpt/metadata/cssom/selectorSerialize.html.ini
@@ -3,24 +3,6 @@
   [:nth-child serialization produces canonical form]
     expected: FAIL
 
-  [single universal selector shows '*' when serialized.]
-    expected: FAIL
-
-  [single type (simple) selector in the sequence of simple selectors that is not a universal selector]
-    expected: FAIL
-
-  [single class (simple) selector in the sequence of simple selectors that is not a universal selector]
-    expected: FAIL
-
-  [single id (simple) selector in the sequence of simple selectors that is not a universal selector]
-    expected: FAIL
-
-  [single pseudo (simple) selector which does not accept arguments in the sequence of simple selectors that is not a universal selector]
-    expected: FAIL
-
-  [single pseudo (simple) selector "lang" which accepts arguments in the sequence of simple selectors that is not a universal selector]
-    expected: FAIL
-
   [single pseudo (simple) selector "nth-child" which accepts arguments in the sequence of simple selectors that is not a universal selector]
     expected: FAIL
 
@@ -33,6 +15,3 @@
   [single pseudo (simple) selector ":nth-last-of-type" which accepts arguments in the sequence of simple selectors that is not a universal selector]
     expected: FAIL
 
-  [single pseudo (simple) selector ":not" which accepts arguments in the sequence of simple selectors that is not a universal selector]
-    expected: FAIL
-
diff --git a/tests/wpt/metadata/cssom/serialize-namespaced-type-selectors.html.ini b/tests/wpt/metadata/cssom/serialize-namespaced-type-selectors.html.ini
index 647031966d7..41f502aee9a 100644
--- a/tests/wpt/metadata/cssom/serialize-namespaced-type-selectors.html.ini
+++ b/tests/wpt/metadata/cssom/serialize-namespaced-type-selectors.html.ini
@@ -1,59 +1,11 @@
 [serialize-namespaced-type-selectors.html]
   type: testharness
-  [Simple type selector]
-    expected: FAIL
-
-  [Type selector without a namespace]
-    expected: FAIL
-
   [Type selector with any namespace]
     expected: FAIL
 
-  [Universal selector]
-    expected: FAIL
-
-  [Universal selector without a namespace]
-    expected: FAIL
-
   [Universal selector in any namespace]
     expected: FAIL
 
-  [Type selector with namespace]
-    expected: FAIL
-
-  [Universal selector with namespace]
-    expected: FAIL
-
-  [Simple type selector followed by class]
-    expected: FAIL
-
-  [Simple type selector followed by id]
-    expected: FAIL
-
-  [Simple type selector followed by pseudo class]
-    expected: FAIL
-
-  [Simple type selector followed by pseudo element]
-    expected: FAIL
-
-  [Simple type selector followed by atttribute selector]
-    expected: FAIL
-
-  [Type selector without a namespace followed by class]
-    expected: FAIL
-
-  [Type selector without a namespace followed by id]
-    expected: FAIL
-
-  [Type selector without a namespace followed by pseudo class]
-    expected: FAIL
-
-  [Type selector without a namespace followed by pseudo element]
-    expected: FAIL
-
-  [Type selector without a namespace followed by attribute selector]
-    expected: FAIL
-
   [Type selector with any namespace followed by class]
     expected: FAIL
 
@@ -84,21 +36,6 @@
   [Universal selector followed by attribute selector]
     expected: FAIL
 
-  [Universal selector without a namespace followed by class]
-    expected: FAIL
-
-  [Universal selector without a namespace followed by id]
-    expected: FAIL
-
-  [Universal selector without a namespace followed by pseudo class]
-    expected: FAIL
-
-  [Universal selector without a namespace followed by pseudo element]
-    expected: FAIL
-
-  [Universal selector without a namespace followed by attribute selector]
-    expected: FAIL
-
   [Universal selector in any namespace followed by class]
     expected: FAIL
 
@@ -114,36 +51,6 @@
   [Universal selector in any namespace followed by attribute selector]
     expected: FAIL
 
-  [Type selector with namespace followed by class]
-    expected: FAIL
-
-  [Type selector with namespace followed by id]
-    expected: FAIL
-
-  [Type selector with namespace followed by pseudo class]
-    expected: FAIL
-
-  [Type selector with namespace followed by pseudo element]
-    expected: FAIL
-
-  [Type selector with namespace followed by attribute selector]
-    expected: FAIL
-
-  [Universal selector with namespace followed by class]
-    expected: FAIL
-
-  [Universal selector with namespace followed by id]
-    expected: FAIL
-
-  [Universal selector with namespace followed by pseudo class]
-    expected: FAIL
-
-  [Universal selector with namespace followed by pseudo element]
-    expected: FAIL
-
-  [Universal selector with namespace followed by attribute selector]
-    expected: FAIL
-
   [Type selector with namespace equal to default namespace]
     expected: FAIL