Fixing superscript and subscript baseline for tiny fonts in SVG

third_party/WebKit/Source/core/layout/svg/SVGTextLayoutEngineBaseline.cpp

Index: third_party/WebKit/Source/core/layout/svg/SVGTextLayoutEngineBaseline.cpp
diff --git a/third_party/WebKit/Source/core/layout/svg/SVGTextLayoutEngineBaseline.cpp b/third_party/WebKit/Source/core/layout/svg/SVGTextLayoutEngineBaseline.cpp
index 560d971671948399be37b02732835171d124d411..bd2f11ecec252e1ef9dc36921a8c15e8d4fefbf2 100644
--- a/third_party/WebKit/Source/core/layout/svg/SVGTextLayoutEngineBaseline.cpp
+++ b/third_party/WebKit/Source/core/layout/svg/SVGTextLayoutEngineBaseline.cpp
@@ -34,7 +34,13 @@ SVGTextLayoutEngineBaseline::SVGTextLayoutEngineBaseline(const Font& font,
 float SVGTextLayoutEngineBaseline::calculateBaselineShift(
     const ComputedStyle& style) const {
   const SVGComputedStyle& svgStyle = style.svgStyle();
-  const SimpleFontData* fontData = m_font.primaryFont();
+  // If font size is smaller than 3, rounding ascent and descent values in
+  // SimpleFontData sets the baseline shifts for superscript and subscript to
+  // zero. In this case,  we use subpixel ascent and descent.
+  const SimpleFontData* fontData =
+      m_font.getFontDescription().getSize().value < 3.0
+          ? m_font.primaryFont()->subpixelAscentDescentFontData().get()
+          : m_font.primaryFont();
   DCHECK(fontData);
   if (!fontData)
     return 0;