Use Length for baselineShiftValue in SVGLayoutStyle

Source/core/layout/svg/SVGTextLayoutEngineBaseline.cpp

Index: Source/core/layout/svg/SVGTextLayoutEngineBaseline.cpp
diff --git a/Source/core/layout/svg/SVGTextLayoutEngineBaseline.cpp b/Source/core/layout/svg/SVGTextLayoutEngineBaseline.cpp
index 113fc8d4e1d6c94dbcc62d021afe5763d32bc3e8..d40e9851017e70aecd460da0573853f80db00ce5 100644
--- a/Source/core/layout/svg/SVGTextLayoutEngineBaseline.cpp
+++ b/Source/core/layout/svg/SVGTextLayoutEngineBaseline.cpp
@@ -24,7 +24,7 @@
 #include "core/layout/LayoutObject.h"
 #include "core/layout/style/SVGLayoutStyle.h"
 #include "core/layout/svg/SVGTextMetrics.h"
-#include "core/svg/SVGLengthContext.h"
+#include "platform/LengthFunctions.h"
 #include "platform/fonts/Font.h"
 #include "platform/text/UnicodeRange.h"
 
@@ -35,20 +35,15 @@ SVGTextLayoutEngineBaseline::SVGTextLayoutEngineBaseline(const Font& font)
 {
 }
 
-float SVGTextLayoutEngineBaseline::calculateBaselineShift(const SVGLayoutStyle& style, SVGElement* contextElement) const
+float SVGTextLayoutEngineBaseline::calculateBaselineShift(const LayoutStyle& style) const
 {
-    if (style.baselineShift() == BS_LENGTH) {
-        RefPtrWillBeRawPtr<SVGLength> baselineShiftValueLength = style.baselineShiftValue();
-        if (baselineShiftValueLength->unitType() == LengthTypePercentage)
-            return baselineShiftValueLength->scaleByPercentage(m_font.fontDescription().computedPixelSize());
+    const SVGLayoutStyle& svgStyle = style.svgStyle();
 
-        SVGLengthContext lengthContext(contextElement);
-        return baselineShiftValueLength->value(lengthContext);
+    switch (svgStyle.baselineShift()) {
+    case BS_LENGTH: {
+        const float zoom = style.effectiveZoom();
+        return floatValueForLength(svgStyle.baselineShiftValue(), m_font.fontDescription().computedPixelSize() * zoom) / zoom;

[pdr., 2015/02/25 19:21:15]

What do you think about moving this zoom calculation to a more central helper
function? (here, or in a later patch)

[fs, 2015/02/25 21:21:11]

I didn't see much use for it, since AFAIK this is a one-off. I suppose we could
do something like:

static float valueForLength(const Length&, float dimension, const LayoutStyle&[,
SVGLengthMode]);

on SVGLengthContext. Should mesh reasonably well with the existing one I think.
If that sounds ok/wanted I'm willing to do that as a follow-up.

     }
-
-    switch (style.baselineShift()) {
-    case BS_BASELINE:
-        return 0;
     case BS_SUB:
         return -m_font.fontMetrics().floatHeight() / 2;
     case BS_SUPER: