[svg2] Make SVGLength wrap a CSSPrimitiveValue

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 0fc04f0ad270edc9d6df18fa4a22119fd402f35d..fac0d2c93ed0be68decdbd1bb4181d3a70e265c5 100644
--- a/Source/core/css/CSSPrimitiveValue.cpp
+++ b/Source/core/css/CSSPrimitiveValue.cpp
@@ -699,6 +699,8 @@ Length CSSPrimitiveValue::convertToLength(const CSSToLengthConversionData& conve
         return computeLength<Length>(conversionData);
     if (isPercentage())
         return Length(getDoubleValue(), Percent);
+    if (isNumber())

[Timothy Loh, 2015/06/03 01:31:08]

Is this something that needs to be here? We currently only use the number type
to represent things which are <number>s in CSS, while unitless lengths (quirks
mode / attributes / zero) will still generate length primitive values.

[Erik Dahlström, 2015/06/03 14:51:30]

This is needed due to
https://codereview.chromium.org/1162453002/patch/40001/50012.

If this is not here, we hit the assert one line down, which causes a bunch of
svg LayoutTest failures. Unitless length values are allowed in svg, and we get
another set of test failures if the parsing of svg lengths allows unitless
values but then represents them as values that had a px unit specified. If the
value was unitless the expectation is that it's preserved that way.

[Timothy Loh, 2015/06/04 02:10:16]

How are we getting into here though? I only see the CSSPrimitiveValue being used
for storage in SVGLength. If the parser change is making other things change, we
should work out a different way to do this part of the patch.

+        return Length(getDoubleValue() * conversionData.zoom(), Fixed);
     ASSERT(isCalculated());
     return Length(cssCalcValue()->toCalcValue(conversionData));
 }