Don't assume line-height properties can't change between text and its container.

third_party/WebKit/Source/core/layout/line/InlineFlowBox.cpp

Index: third_party/WebKit/Source/core/layout/line/InlineFlowBox.cpp
diff --git a/third_party/WebKit/Source/core/layout/line/InlineFlowBox.cpp b/third_party/WebKit/Source/core/layout/line/InlineFlowBox.cpp
index 51c7e5867a9d56b3e7465a196be420fa45c28f45..7c3f4e313888223627c7cc39063294a878c33085 100644
--- a/third_party/WebKit/Source/core/layout/line/InlineFlowBox.cpp
+++ b/third_party/WebKit/Source/core/layout/line/InlineFlowBox.cpp
@@ -91,6 +91,12 @@ static inline bool HasIdenticalLineHeightProperties(
          child_style.VerticalAlign() == EVerticalAlign::kBaseline;
 }
 
+static inline bool ParentIsDOMParent(LineLayoutItem parent,
+                                     LineLayoutItem child) {
+  return child.GetNode() &&
+         FlatTreeTraversal::Parent(*child.GetNode()) == parent.GetNode();

[eae, 2017/04/21 10:54:52]

Can child.GetNode() ever be null? Might be worth adding a DCHECK here.

+}
+
 void InlineFlowBox::AddToLine(InlineBox* child) {
   DCHECK(!child->Parent());
   DCHECK(!child->NextOnLine());
@@ -129,7 +135,8 @@ void InlineFlowBox::AddToLine(InlineBox* child) {
       should_clear_descendants_have_same_line_height_and_baseline = true;
     } else if (child->IsText()) {
       if (child->GetLineLayoutItem().IsBR() ||
-          (child->GetLineLayoutItem().Parent() != GetLineLayoutItem())) {
+          child->GetLineLayoutItem().Parent() != GetLineLayoutItem() ||
+          !ParentIsDOMParent(GetLineLayoutItem(), child->GetLineLayoutItem())) {
         if (!HasIdenticalLineHeightProperties(parent_style, child_style, root))
           should_clear_descendants_have_same_line_height_and_baseline = true;
       }