[CSS Grid Layout] Use CSS_FR for flexible lengths instead of CSS_DIMENSION

Source/core/css/CSSPrimitiveValue.cpp

Index: Source/core/css/CSSPrimitiveValue.cpp
diff --git a/Source/core/css/CSSPrimitiveValue.cpp b/Source/core/css/CSSPrimitiveValue.cpp
index a77565b0bd66985417327c76864ae20775661868..708970eda0382257e19b9997d26f6cd24f53c3e8 100644
--- a/Source/core/css/CSSPrimitiveValue.cpp
+++ b/Source/core/css/CSSPrimitiveValue.cpp
@@ -988,7 +988,7 @@ String CSSPrimitiveValue::customCssText(CssTextFormattingFlags formattingFlag) c
             text = formatNumber(m_value.num, "turn");
             break;
         case CSS_DIMENSION:
-            text = m_value.string;
+            // FIXME

[Julien - ping for review, 2013/09/13 16:44:51]

I don't like this change, even if you are reverting the code to its original
state for one reason: the FIXME is *not actionable*. If I read it, I have no
clue what I should (or shouldn't) do.

I would just put the following instead:

// FIXME: We currently don't handle CSS_DIMENSION properly as we don't store the
actual dimension, just the numeric value as a string.

             break;
         case CSS_STRING:
             text = formattingFlag == AlwaysQuoteCSSString ? quoteCSSString(m_value.string) : quoteCSSStringIfNeeded(m_value.string);