Fix ASSERT failure in RenderGeomtryMap for SVGs

Source/core/rendering/svg/SVGRenderSupport.cpp

Index: Source/core/rendering/svg/SVGRenderSupport.cpp
diff --git a/Source/core/rendering/svg/SVGRenderSupport.cpp b/Source/core/rendering/svg/SVGRenderSupport.cpp
index 99871c7b9142b52b5a8a6b59b4f5d26958c7adba..ef38ba008e9e4320ba619084c1860ed227a7bd6a 100644
--- a/Source/core/rendering/svg/SVGRenderSupport.cpp
+++ b/Source/core/rendering/svg/SVGRenderSupport.cpp
@@ -67,8 +67,6 @@ void SVGRenderSupport::computeFloatRectForRepaint(const RenderObject* object, co
 
 void SVGRenderSupport::mapLocalToContainer(const RenderObject* object, const RenderLayerModelObject* repaintContainer, TransformState& transformState, bool* wasFixed)
 {
-    transformState.applyTransform(object->localToParentTransform());
-
     RenderObject* parent = object->parent();
 
     // At the SVG/HTML boundary (aka RenderSVGRoot), we apply the localToBorderBoxTransform
@@ -77,6 +75,8 @@ void SVGRenderSupport::mapLocalToContainer(const RenderObject* object, const Ren
     if (parent->isSVGRoot())
         transformState.applyTransform(toRenderSVGRoot(parent)->localToBorderBoxTransform());
 
+    transformState.applyTransform(object->localToParentTransform());

[fs, 2014/01/21 09:07:57]

This doesn't look right to me - I take it that in the relevant case, |object| is
the <g transform="scale(3)">, and hence that |parent| is the <svg ...>? If so,
then the currently local coordinate space is the coordinate space of the <g> -
from which we get to the local coordinate space of the <svg> by applying the
scale(3) - yes? Then to get to the "CSS (border) box" space by applying the
transform produced by the viewBox (mapping the content-box width/height to a
specified local coordinate space). And then RenderBox adds in any extras. Or
maybe it's me missing something? =)

[Stephen Chennney, 2014/01/21 22:12:11]

I think that, like me, you are confused by the ambiguity of "applyTransform",
which apparently multiplies it to the current transform on the right. In other
words, the last transform to be applied in code will actually be the first one
applied mathematically. I don't know who wrote this, but it's as confusing as
can be.

+
     MapCoordinatesFlags mode = UseTransforms;
     parent->mapLocalToContainer(repaintContainer, transformState, mode, wasFixed);
 }