From 040c09fbc51ac282b7224799851d62cd3a60ee7f Mon Sep 17 00:00:00 2001
From: Matt Brubeck <mbrubeck@limpet.net>
Date: Thu, 17 Sep 2015 08:36:27 -0700
Subject: [PATCH 1/2] Always reset HAS_NEWLY_CONSTRUCTED_FLOW during flow
 construction

This extra reflows when the HAS_NEWLY_CONSTRUCTED_FLOW flag remained set
during a later reflow.  This masked other incremental layout bugs, including
the one tested by the reftest in the commit following this one.
---
 components/layout/construct.rs | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/components/layout/construct.rs b/components/layout/construct.rs
index dd1d58a6acc..d7e1628dd38 100644
--- a/components/layout/construct.rs
+++ b/components/layout/construct.rs
@@ -1296,10 +1296,9 @@ impl<'a> FlowConstructor<'a> {
     pub fn repair_if_possible(&mut self, node: &ThreadSafeLayoutNode) -> bool {
         // We can skip reconstructing the flow if we don't have to reconstruct and none of our kids
         // did either.
-        if node.restyle_damage().contains(RECONSTRUCT_FLOW) {
-            return false
-        }
-
+        //
+        // We visit the kids first and reset their HAS_NEWLY_CONSTRUCTED_FLOW flags after checking
+        // them.  NOTE: Make sure not to bail out early before resetting all the flags!
         let mut need_to_reconstruct = false;
         for kid in node.children() {
             if kid.flags().contains(HAS_NEWLY_CONSTRUCTED_FLOW) {
@@ -1311,6 +1310,11 @@ impl<'a> FlowConstructor<'a> {
             return false
         }
 
+        if node.restyle_damage().contains(RECONSTRUCT_FLOW) {
+            return false
+        }
+
+
         let mut style = node.style().clone();
         let mut layout_data_ref = node.mutate_layout_data();
         let layout_data = layout_data_ref.as_mut().expect("no layout data");

From 0c77705f522fe74c4d5df91474226fa5b3b1e5a2 Mon Sep 17 00:00:00 2001
From: Matt Brubeck <mbrubeck@limpet.net>
Date: Thu, 17 Sep 2015 04:46:32 -0700
Subject: [PATCH 2/2] Reconstruct flows when text/font/list styles change

Fixes #6501.
---
 components/layout/incremental.rs              | 15 ++++++++++++---
 tests/ref/basic.list                          |  1 +
 tests/ref/incremental_letter_spacing_a.html   | 15 +++++++++++++++
 tests/ref/incremental_letter_spacing_ref.html | 10 ++++++++++
 4 files changed, 38 insertions(+), 3 deletions(-)
 create mode 100644 tests/ref/incremental_letter_spacing_a.html
 create mode 100644 tests/ref/incremental_letter_spacing_ref.html

diff --git a/components/layout/incremental.rs b/components/layout/incremental.rs
index 14205b32cb5..adabc4bb471 100644
--- a/components/layout/incremental.rs
+++ b/components/layout/incremental.rs
@@ -175,13 +175,22 @@ pub fn compute_damage(old: &Option<Arc<ComputedValues>>, new: &ComputedValues) -
         get_padding.padding_top, get_padding.padding_right,
         get_padding.padding_bottom, get_padding.padding_left,
         get_box.width, get_box.height,
-        get_font.font_family, get_font.font_size, get_font.font_style, get_font.font_weight,
         get_inheritedtext.text_align, get_text.text_decoration, get_inheritedbox.line_height
     ]);
 
     add_if_not_equal!(old, new, damage,
-                      [ REPAINT, BUBBLE_ISIZES, REFLOW_OUT_OF_FLOW, REFLOW, RECONSTRUCT_FLOW ],
-                      [ get_box.float, get_box.display, get_box.position ]);
+                      [ REPAINT, BUBBLE_ISIZES, REFLOW_OUT_OF_FLOW, REFLOW, RECONSTRUCT_FLOW ], [
+        get_box.float, get_box.display, get_box.position, get_box.content,
+        get_counters.counter_reset, get_counters.counter_increment,
+        get_list.quotes, get_list.list_style_type,
+
+        // If these text or font properties change, we need to reconstruct the flow so that
+        // text shaping is re-run.
+        get_inheritedtext.letter_spacing, get_inheritedtext.text_rendering,
+        get_inheritedtext.text_transform, get_inheritedtext.word_spacing,
+        get_font.font_family, get_font.font_style, get_font.font_variant, get_font.font_weight,
+        get_font.font_size, get_font.font_stretch
+    ]);
 
     // FIXME: test somehow that we checked every CSS property
     damage
diff --git a/tests/ref/basic.list b/tests/ref/basic.list
index 65ae2cce853..311a02b86c9 100644
--- a/tests/ref/basic.list
+++ b/tests/ref/basic.list
@@ -160,6 +160,7 @@ prefs:"layout.writing-mode.enabled" == iframe/size_attributes_vertical_writing_m
 == img_width_style_intrinsic_width_a.html img_width_style_intrinsic_width_ref.html
 == incremental_float_a.html incremental_float_ref.html
 == incremental_inline_layout_a.html incremental_inline_layout_ref.html
+== incremental_letter_spacing_a.html incremental_letter_spacing_ref.html
 == inline_absolute_hypothetical_clip_a.html inline_absolute_hypothetical_clip_ref.html
 == inline_absolute_out_of_flow_a.html inline_absolute_out_of_flow_ref.html
 != inline_background_a.html inline_background_ref.html
diff --git a/tests/ref/incremental_letter_spacing_a.html b/tests/ref/incremental_letter_spacing_a.html
new file mode 100644
index 00000000000..351cd100d05
--- /dev/null
+++ b/tests/ref/incremental_letter_spacing_a.html
@@ -0,0 +1,15 @@
+<!DOCTYPE html>
+<html>
+  <head>
+    <meta charset="UTF-8">
+    <title>Incremental layout letter-spacing test</title>
+  </head>
+  <body>
+    <p>Hello, world!</p>
+    <script>
+      window.addEventListener("load", function() {
+        document.querySelector("p").style.letterSpacing = "1em";
+      });
+    </script>
+  </body>
+</html>
diff --git a/tests/ref/incremental_letter_spacing_ref.html b/tests/ref/incremental_letter_spacing_ref.html
new file mode 100644
index 00000000000..0c1f3004bdd
--- /dev/null
+++ b/tests/ref/incremental_letter_spacing_ref.html
@@ -0,0 +1,10 @@
+<!DOCTYPE html>
+<html>
+  <head>
+    <meta charset="UTF-8">
+    <title>Incremental layout letter-spacing reference</title>
+  </head>
+  <body>
+    <p style="letter-spacing: 1em">Hello, world!</p>
+  </body>
+</html>