Use glyph-ids for lookups of SVG font kerning-pairs

Source/core/rendering/svg/SVGTextMetrics.cpp

Index: Source/core/rendering/svg/SVGTextMetrics.cpp
diff --git a/Source/core/rendering/svg/SVGTextMetrics.cpp b/Source/core/rendering/svg/SVGTextMetrics.cpp
index 26c82dbec27c168bde69ded737f9409546fb1dbf..e9bacb475efa3bb09d4aff152610f9d86a10aad6 100644
--- a/Source/core/rendering/svg/SVGTextMetrics.cpp
+++ b/Source/core/rendering/svg/SVGTextMetrics.cpp
@@ -30,6 +30,7 @@ SVGTextMetrics::SVGTextMetrics()
     : m_width(0)
     , m_height(0)
     , m_length(0)
+    , m_glyph(0)
 {
 }
 
@@ -37,6 +38,7 @@ SVGTextMetrics::SVGTextMetrics(SVGTextMetrics::MetricsType)
     : m_width(0)
     , m_height(0)
     , m_length(1)
+    , m_glyph(0)
 {
 }
 
@@ -51,12 +53,9 @@ SVGTextMetrics::SVGTextMetrics(RenderSVGInlineText* textRenderer, const TextRun&
     int length = 0;
 
     // Calculate width/height using the scaled font, divide this result by the scalingFactor afterwards.
-    m_width = scaledFont.width(run, length, m_glyph.name) / scalingFactor;
+    m_width = scaledFont.width(run, length, m_glyph) / scalingFactor;
     m_height = scaledFont.fontMetrics().floatHeight() / scalingFactor;
 
-    m_glyph.unicodeString = run.is8Bit() ? String(run.characters8(), length) : String(run.characters16(), length);
-    m_glyph.isValid = true;
-
     ASSERT(length >= 0);
     m_length = static_cast<unsigned>(length);
 }
@@ -101,7 +100,7 @@ SVGTextMetrics SVGTextMetrics::measureCharacterRange(RenderSVGInlineText* text,
     return SVGTextMetrics(text, constructTextRun(text, position, length));
 }
 
-SVGTextMetrics::SVGTextMetrics(RenderSVGInlineText* text, unsigned position, unsigned length, float width, const String& glyphName)
+SVGTextMetrics::SVGTextMetrics(RenderSVGInlineText* text, unsigned position, unsigned length, float width, Glyph glyphNameGlyphId)
 {
     ASSERT(text);
 
@@ -111,11 +110,7 @@ SVGTextMetrics::SVGTextMetrics(RenderSVGInlineText* text, unsigned position, uns
 
     m_width = width / scalingFactor;
     m_height = text->scaledFont().fontMetrics().floatHeight() / scalingFactor;
-    if (needsContext) {
-        m_glyph.isValid = true;
-        m_glyph.unicodeString = text->substring(position, length);
-        m_glyph.name = glyphName;
-    }
+    m_glyph = needsContext ? glyphNameGlyphId : 0;
 
     m_length = length;
 }