Track the region where text is painted.

Source/core/platform/graphics/GraphicsContext.cpp

Index: Source/core/platform/graphics/GraphicsContext.cpp
diff --git a/Source/core/platform/graphics/GraphicsContext.cpp b/Source/core/platform/graphics/GraphicsContext.cpp
index d3b6aa1ea6c78abdb4096223185fa3bd575eb9c4..3bcda353c03a35011233533f1ee3711b61948bcb 100644
--- a/Source/core/platform/graphics/GraphicsContext.cpp
+++ b/Source/core/platform/graphics/GraphicsContext.cpp
@@ -871,27 +871,30 @@ void GraphicsContext::drawRect(const IntRect& rect)
     platformContext()->drawRect(rect);
 }
 
-void GraphicsContext::drawText(const Font& font, const TextRun& run, const FloatPoint& point, int from, int to)
+void GraphicsContext::drawText(const Font& font, const TextRunPaintInfo& runInfo, const FloatPoint& point)
 {
     if (paintingDisabled())
         return;
 
-    font.drawText(this, run, point, from, to);
+    font.drawText(this, runInfo, point);
 }
 
-void GraphicsContext::drawEmphasisMarks(const Font& font, const TextRun& run, const AtomicString& mark, const FloatPoint& point, int from, int to)
+void GraphicsContext::drawEmphasisMarks(const Font& font, const TextRunPaintInfo& runInfo, const AtomicString& mark, const FloatPoint& point)
 {
     if (paintingDisabled())
         return;
 
-    font.drawEmphasisMarks(this, run, mark, point, from, to);
+    font.drawEmphasisMarks(this, runInfo, mark, point);
 }
 
-void GraphicsContext::drawBidiText(const Font& font, const TextRun& run, const FloatPoint& point, Font::CustomFontNotReadyAction customFontNotReadyAction)
+void GraphicsContext::drawBidiText(const Font& font, const TextRunPaintInfo& runInfo, const FloatPoint& point, Font::CustomFontNotReadyAction customFontNotReadyAction)
 {
     if (paintingDisabled())
         return;
 
+    // sub-run painting is not supported for Bidi text.
+    const TextRun& run = runInfo.run;
+    ASSERT((runInfo.from == 0) && (runInfo.to == run.length()));
     BidiResolver<TextRunIterator, BidiCharacterRun> bidiResolver;
     bidiResolver.setStatus(BidiStatus(run.direction(), run.directionalOverride()));
     bidiResolver.setPositionIgnoringNestedIsolates(TextRunIterator(&run, 0));
@@ -911,7 +914,9 @@ void GraphicsContext::drawBidiText(const Font& font, const TextRun& run, const F
         subrun.setDirection(isRTL ? RTL : LTR);
         subrun.setDirectionalOverride(bidiRun->dirOverride(false));
 
-        font.drawText(this, subrun, currPoint, 0, -1, customFontNotReadyAction);
+        TextRunPaintInfo subrunInfo(subrun);
+        subrunInfo.bounds = runInfo.bounds;
+        font.drawText(this, subrunInfo, currPoint, customFontNotReadyAction);
 
         bidiRun = bidiRun->next();
         // FIXME: Have Font::drawText return the width of what it drew so that we don't have to re-measure here.