Add plumbing for font-stretch

Source/core/css/resolver/AnimatedStyleBuilder.cpp

Index: Source/core/css/resolver/AnimatedStyleBuilder.cpp
diff --git a/Source/core/css/resolver/AnimatedStyleBuilder.cpp b/Source/core/css/resolver/AnimatedStyleBuilder.cpp
index 50f2f24cc60ba6c4bc0fa906c0fac3289b3be256..3a6b0ff0188bc1211c943179821bf4b13b58fb27 100644
--- a/Source/core/css/resolver/AnimatedStyleBuilder.cpp
+++ b/Source/core/css/resolver/AnimatedStyleBuilder.cpp
@@ -225,6 +225,26 @@ void setOnFillLayers(FillLayer* fillLayer, const AnimatableValue* value, StyleRe
     }
 }
 
+FontStretch animatableValueToFontStretch(const AnimatableValue* value)
+{
+    ASSERT(FontStretchUltraCondensed == 1 && FontStretchUltraExpanded == 9);
+    unsigned index = round(toAnimatableDouble(value)->toDouble()) - 1;
+    static const FontStretch stretchValues[] = {
+        FontStretchUltraCondensed,
+        FontStretchExtraCondensed,
+        FontStretchCondensed,
+        FontStretchSemiCondensed,
+        FontStretchNormal,
+        FontStretchSemiExpanded,
+        FontStretchExpanded,
+        FontStretchExtraExpanded,
+        FontStretchUltraExpanded
+    };
+
+    index = clampTo<unsigned>(index, 0, WTF_ARRAY_LENGTH(stretchValues) - 1);
+    return stretchValues[index];
+}
+
 FontWeight animatableValueToFontWeight(const AnimatableValue* value)
 {
     int index = round(toAnimatableDouble(value)->toDouble() / 100) - 1;
@@ -372,6 +392,9 @@ void AnimatedStyleBuilder::applyProperty(CSSPropertyID property, StyleResolverSt
     case CSSPropertyFontSize:
         style->setFontSize(clampTo<float>(toAnimatableDouble(value)->toDouble(), 0));
         return;
+    case CSSPropertyFontStretch:
+        style->setFontStretch(animatableValueToFontStretch(value));
+        return;
     case CSSPropertyFontWeight:
         style->setFontWeight(animatableValueToFontWeight(value));
         return;