Move viewport unit resolution to style recalc time

Source/platform/Length.h

Index: Source/platform/Length.h
diff --git a/Source/platform/Length.h b/Source/platform/Length.h
index 60d20e9703020e01f31274f72d37042f6fda1f53..9048d49bf30f80e525c22fa869a5515e5d89f30f 100644
--- a/Source/platform/Length.h
+++ b/Source/platform/Length.h
@@ -35,13 +35,14 @@
 
 namespace WebCore {
 
+// FIXME: This enum makes it hard to tell in general what values may be
+// appropriate for any given Length.
 enum LengthType {
     Auto, Percent, Fixed,
     Intrinsic, MinIntrinsic,
     MinContent, MaxContent, FillAvailable, FitContent,
     Calculated,
-    ViewportPercentageWidth, ViewportPercentageHeight, ViewportPercentageMin, ViewportPercentageMax,
-    ExtendToZoom,
+    ExtendToZoom, DeviceWidth, DeviceHeight,

[johnme, 2013/12/18 12:04:15]

I'm probably missing something, but why did you add DeviceWidth and DeviceHeight
here? Shouldn't they always behave identically to 100vw and 100vh (bearing in
mind that vw/vh behave differently in @viewport, being relative to the initial
viewport there[1], rather than the layout viewport (ICB) like they usually
are[2])?

[1]: http://dev.w3.org/csswg/css-device-adapt/#viewport-descriptors
[2]: http://www.w3.org/TR/css3-values/#viewport-relative-lengths

[Timothy Loh, 2013/12/23 06:28:16]

See other comments about vw/vh meaning.

This seems like the simplest way to handle this to me. Resolving these here just
complicates the logic around resizing since we'd have to update these also. Also
calling document::setHasViewportUnits would be a bit odd here, since we don't
actually have viewport units!

     Undefined
 };
 
@@ -229,7 +230,7 @@ public:
     bool isIntrinsicOrAuto() const { return type() == Auto || isLegacyIntrinsic() || isIntrinsic(); }
     bool isLegacyIntrinsic() const { return type() == Intrinsic || type() == MinIntrinsic; }
     bool isIntrinsic() const { return type() == MinContent || type() == MaxContent || type() == FillAvailable || type() == FitContent; }
-    bool isSpecified() const { return type() == Fixed || type() == Percent || type() == Calculated || isViewportPercentage(); }
+    bool isSpecified() const { return type() == Fixed || type() == Percent || type() == Calculated; }
     bool isSpecifiedOrIntrinsic() const { return isSpecified() || isIntrinsic(); }
     bool isCalculated() const { return type() == Calculated; }
     bool isCalculatedEqual(const Length&) const;
@@ -277,16 +278,6 @@ public:
     }
     float nonNanCalculatedValue(int maxValue) const;
 
-    bool isViewportPercentage() const
-    {
-        LengthType lengthType = type();
-        return lengthType >= ViewportPercentageWidth && lengthType <= ViewportPercentageMax;
-    }
-    float viewportPercentageLength() const
-    {
-        ASSERT(isViewportPercentage());
-        return getFloatValue();
-    }
 private:
     int getIntValue() const
     {