Rework SVG sizing

Source/core/css/svg.css

Index: Source/core/css/svg.css
diff --git a/Source/core/css/svg.css b/Source/core/css/svg.css
index f860d7baade51651650aab15f3170139dfd39222..fa1f0ff054ec621f18ab909508ebea9b91289954 100644
--- a/Source/core/css/svg.css
+++ b/Source/core/css/svg.css
@@ -47,6 +47,12 @@ svg:not(:root), symbol, image, marker, pattern, foreignObject {
     overflow: hidden
 }
 
+svg:root {
+    height: 100%;
+    width: 100%;
+    position: absolute

[pdr., 2014/04/15 02:46:10]

position: absolute seems odd to me. Can you talk a bit about why it's needed?

[davve, 2014/04/15 15:55:23]

I have this on my list of things to do. Current ramblings:

position: absolute is a bit of a hack to get the height percentage value to
resolve against the viewport dimensions. Could and should probably be replaced
with a corresponding "hack"/fix in the c++ code instead, somewhere in
RenderReplaced::hasReplacedLogicalHeight() or
RenderBoxModelObject::hasAutoHeightOrContainingBlockWithAutoHeight().

The RenderView (containing block of the root svg) has style height:auto, so we
need to avoid falling into turning height: 100% into height: auto in some way.
As for position:absolute, hasAutoHeightOrContainingBlockWithAutoHeight has a
check for isOutOfFlowPositioned() that makes us able to resolve the height to
the viewport (since position:absolute stuff is outside normal flow it doesn't
contribute to auto height ancestors thus it being safe to resolve it percentages
without loops).

I will continue to look into this.

[davve, 2014/04/16 14:35:30]

Addressed by allowing boxes to resolve percentages against the frame. See
RenderBoxModelObject::hasAutoHeightOrContainingBlockWithAutoHeight in patch set
14 and later.

+}
+
 text, foreignObject {
     display: block
 }