Fix "unreachable code" warnings (MSVC warning 4702) in Blink.

Source/core/rendering/RenderBox.cpp

Index: Source/core/rendering/RenderBox.cpp
===================================================================
--- Source/core/rendering/RenderBox.cpp	(revision 169196)
+++ Source/core/rendering/RenderBox.cpp	(working copy)
@@ -355,10 +355,11 @@
 {
     // FIXME: This optimization is incorrect as written.
     // We need to be able to opt-in to this behavior only when
-    // it's guarentted correct.
+    // it's guaranteed correct.
     // Until then disabling this optimization to be safe.
+#if 1

[Nico, 2014/03/18 17:47:51]

Just delete this code; if Eric wants to pick this up again he can get it from
svn. (The FIXME has been here for several months.)

[eseidel, 2014/03/18 18:10:23]

Sorry, this was an emergency fix done for a stable-blocker for M31, which was
rolling out tony's optimization.  We should just remove the whole codepath now. 
We have no plans to persue that optimization further.

[Peter Kasting, 2014/03/18 20:58:04]

Eric, would you be willing to make this change separately?  I'm happy to either
wait on it or to land this as-is, whatever you prefer.  I looked briefly at just
removing this function, but one of the callers has scary-sounding "this check is
likely wrong!" sorts of language that makes me gunshy about touching it myself
when I understand nothing about what it's doing.

[Nico, 2014/03/19 10:20:05]

You can change the function body to "
  // FIXME: remove function and callers
  return false;
"

[Peter Kasting, 2014/03/19 20:50:01]

Done.

     return false;
-
+#else
     // FIXME: There are likely many subclasses of RenderBlockFlow which
     // cannot determine their layout just from style!
     // Perhaps we should create a "PlainRenderBlockFlow"
@@ -377,6 +378,7 @@
         && style->paddingLeft().isFixed()
         && style->paddingRight().isFixed()
         && style->boxSizing() == CONTENT_BOX;
+#endif
 }
 
 LayoutUnit RenderBox::fixedOffsetWidth() const