Fixes a crash when copying elements with font-weight lighter or bolder

Source/core/editing/EditingStyle.cpp

Index: Source/core/editing/EditingStyle.cpp
diff --git a/Source/core/editing/EditingStyle.cpp b/Source/core/editing/EditingStyle.cpp
index 614038c2de9597891c66cd616b64410bf9c9d821..bc20bf2511a62aad56a3d0445e6e6371cf165483 100644
--- a/Source/core/editing/EditingStyle.cpp
+++ b/Source/core/editing/EditingStyle.cpp
@@ -1505,9 +1505,11 @@ static bool fontWeightIsBold(CSSValue* fontWeight)
         case CSSValue300:
         case CSSValue400:
         case CSSValue500:
+        case CSSValueLighter:
         case CSSValueNormal:
             return false;
         case CSSValueBold:
+        case CSSValueBolder:

[rniwa-cr, 2013/08/13 20:52:53]

This is incorrect. e.g. in
<span style="font-weight: 100;">hello <span
style="font-weight:bolder">world</span></span>
"world" is not bolded.

To properly fix this bug, we need to do it in its caller and resolve the used
value through the render tree.

         case CSSValue600:
         case CSSValue700:
         case CSSValue800:
@@ -1517,7 +1519,7 @@ static bool fontWeightIsBold(CSSValue* fontWeight)
             break;
     }
 
-    ASSERT_NOT_REACHED(); // For CSSValueBolder and CSSValueLighter

[esprehn, 2013/08/13 20:07:43]

Why was this comment here? It seems the author thought this code was unreachable
and those values should never be here.

+    ASSERT_NOT_REACHED();
     return false;
 }