Auto merge of #10834 - yoava333:master, r=SimonSapin

added support for :read-only and :read-write pseudo-classes

partial fix for https://github.com/servo/servo/issues/10732

It's not a full fix because:
1. there's a bug in wpt-test https://github.com/w3c/web-platform-tests/issues/2889#issuecomment-214144420
2. we don't fully support all input types (namely image, color, hidden and range), which are defaulted to input text. this means that :read-write which is applicable to input text is mis-handled in those cases.
3. we don't support contenteditable, which is also possibly :read-write

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ports/geckolib/selector_impl.rs

@@ -101,6 +101,8 @@ pub enum NonTSPseudoClass {
     Disabled,
     Checked,
     Indeterminate,
+    ReadWrite,
+    ReadOnly,
 }
 
 impl NonTSPseudoClass {
@@ -115,6 +117,7 @@ impl NonTSPseudoClass {
             Disabled => IN_DISABLED_STATE,
             Checked => IN_CHECKED_STATE,
             Indeterminate => IN_INDETERMINATE_STATE,
+            ReadOnly | ReadWrite => IN_READ_WRITE_STATE,
 
             AnyLink |
             Link |
@@ -140,6 +143,8 @@ impl SelectorImpl for GeckoSelectorImpl {
             "disabled" => Disabled,
             "checked" => Checked,
             "indeterminate" => Indeterminate,
+            "read-write" => ReadWrite,
+            "read-only" => ReadOnly,
             _ => return Err(())
         };
 

ports/geckolib/wrapper.rs

@@ -437,9 +437,13 @@ impl<'le> ::selectors::Element for GeckoElement<'le> {
             NonTSPseudoClass::Enabled |
             NonTSPseudoClass::Disabled |
             NonTSPseudoClass::Checked |
+            NonTSPseudoClass::ReadWrite |
             NonTSPseudoClass::Indeterminate => {
                 self.get_state().contains(pseudo_class.state_flag())
             },
+            NonTSPseudoClass::ReadOnly => {
+                !self.get_state().contains(pseudo_class.state_flag())
+            }
         }
     }