Add toSVGRootInlineBox(), and use it as much as we can

Source/core/rendering/RenderBlockLineLayout.cpp

Index: Source/core/rendering/RenderBlockLineLayout.cpp
diff --git a/Source/core/rendering/RenderBlockLineLayout.cpp b/Source/core/rendering/RenderBlockLineLayout.cpp
index 1d0408eed45cf925f959c8dac35128090df9cc11..fd69862a2dd469628aa1898948f8afb0ba9939f9 100644
--- a/Source/core/rendering/RenderBlockLineLayout.cpp
+++ b/Source/core/rendering/RenderBlockLineLayout.cpp
@@ -1445,12 +1445,10 @@ RootInlineBox* RenderBlock::createLineBoxesFromBidiRuns(unsigned bidiLevel, Bidi
     lineBox->setBidiLevel(bidiLevel);
     lineBox->setEndsWithBreak(lineInfo.previousLineBrokeCleanly());
 
-    bool isSVGRootInlineBox = lineBox->isSVGRootInlineBox();

[tkent, 2013/09/12 22:45:13]

You don't need to remove this local variable.  isSVGRootInlineBox() is a virtual
function, and calling it requires some cost though it's very small.

-
     GlyphOverflowAndFallbackFontsMap textBoxDataMap;
 
     // Now we position all of our text runs horizontally.
-    if (!isSVGRootInlineBox)
+    if (!lineBox->isSVGRootInlineBox())
         computeInlineDirectionPositionsForLine(lineBox, lineInfo, bidiRuns.firstRun(), trailingSpaceRun, end.atEnd(), textBoxDataMap, verticalPositionCache, wordMeasurements);
 
     // Now position our text runs vertically.
@@ -1461,9 +1459,9 @@ RootInlineBox* RenderBlock::createLineBoxesFromBidiRuns(unsigned bidiLevel, Bidi
     // it calls InlineTextBox::positionLineBox(), which tracks whether the box
     // contains reversed text or not. If we wouldn't do that editing and thus
     // text selection in RTL boxes would not work as expected.
-    if (isSVGRootInlineBox) {
+    if (lineBox->isSVGRootInlineBox()) {
         ASSERT(isSVGText());
-        static_cast<SVGRootInlineBox*>(lineBox)->computePerCharacterLayoutInformation();
+        toSVGRootInlineBox(lineBox)->computePerCharacterLayoutInformation();
     }
 
     // Compute our overflow now.