Disable offsetWidth optimization in perparation for disabling it on M30.

Source/core/rendering/RenderBox.cpp

Index: Source/core/rendering/RenderBox.cpp
diff --git a/Source/core/rendering/RenderBox.cpp b/Source/core/rendering/RenderBox.cpp
index 84f11e672d2eb3c9686e9e5df2477c6fd974017a..0474d3bf906d94137232fa4511d291a8440de582 100644
--- a/Source/core/rendering/RenderBox.cpp
+++ b/Source/core/rendering/RenderBox.cpp
@@ -410,7 +410,12 @@ int RenderBox::pixelSnappedOffsetHeight() const
 
 bool RenderBox::canDetermineWidthWithoutLayout() const
 {
-    // THIS OPTIMIZATION IS INCORRECT AS WRITTEN.
+    // FIXME: This optimization is incorrect as written.
+    // We need to be able to opt-in to this behavior only when
+    // it's guarentted correct.

[abarth-chromium, 2013/10/07 21:17:47]

typo: guarentted

+    // Until then disabling this optimization to be safe.
+    return false;
+
     // FIXME: There are likely many subclasses of RenderBlockFlow which
     // cannot determine their layout just from style!
     // Perhaps we should create a "PlainRenderBlockFlow"