Add a fast path to CSSParserFastPaths for CSS transform rotate.

third_party/WebKit/Source/core/css/parser/CSSParserFastPaths.cpp

Index: third_party/WebKit/Source/core/css/parser/CSSParserFastPaths.cpp
diff --git a/third_party/WebKit/Source/core/css/parser/CSSParserFastPaths.cpp b/third_party/WebKit/Source/core/css/parser/CSSParserFastPaths.cpp
index 768add52802b42578eee606f601bf66e7054eaa2..6c3b49aa0a032847d81d1f19d2955434d8cdb17a 100644
--- a/third_party/WebKit/Source/core/css/parser/CSSParserFastPaths.cpp
+++ b/third_party/WebKit/Source/core/css/parser/CSSParserFastPaths.cpp
@@ -900,6 +900,31 @@ static bool parseTransformNumberArguments(CharType*& pos, CharType* end, unsigne
 }
 
 template <typename CharType>
+static bool parseTransformRotateArguments(CharType*& pos, CharType* end, CSSFunctionValue* transformValue)
+{
+    static const int kDegLength = 3;
+
+    size_t delimiter = WTF::find(pos, end - pos, ')');
+    if (delimiter == kNotFound)
+        return false;
+    CharType* degreeStart = pos + delimiter - kDegLength;
+    bool isDegree = degreeStart > pos // require at least one digit.
+        && toASCIILower(degreeStart[0]) == 'd'
+        && toASCIILower(degreeStart[1]) == 'e'
+        && toASCIILower(degreeStart[2]) == 'g';
+    if (!isDegree)
+        return false;
+    unsigned argumentLength = static_cast<unsigned>(delimiter - kDegLength);
+    bool ok;
+    double number = charactersToDouble(pos, argumentLength, &ok);
+    if (!ok)
+        return false;
+    transformValue->append(cssValuePool().createValue(number, CSSPrimitiveValue::UnitType::Degrees));
+    pos += delimiter + 1;
+    return true;
+}
+
+template <typename CharType>
 static CSSFunctionValue* parseSimpleTransformValue(CharType*& pos, CharType* end)
 {
     static const int shortestValidTransformStringLength = 12;
@@ -981,6 +1006,36 @@ static CSSFunctionValue* parseSimpleTransformValue(CharType*& pos, CharType* end
         return transformValue;
     }
 
+    const bool isRotate = toASCIILower(pos[0]) == 'r'
+        && toASCIILower(pos[1]) == 'o'
+        && toASCIILower(pos[2]) == 't'
+        && toASCIILower(pos[3]) == 'a'
+        && toASCIILower(pos[4]) == 't'
+        && toASCIILower(pos[5]) == 'e';
+
+    if (isRotate) {
+        CSSValueID transformType;
+        unsigned argumentStart = 8;
+        CharType c6 = toASCIILower(pos[6]);
+        if (c6 == 'x' && pos[7] == '(') {
+            transformType = CSSValueRotateX;
+        } else if (c6 == 'y' && pos[7] == '(') {
+            transformType = CSSValueRotateY;
+        } else if (c6 == 'z' && pos[7] == '(') {
+            transformType = CSSValueRotateZ;
+        } else if (c6 == '(') {
+            transformType = CSSValueRotate;
+            argumentStart = 7;
+        } else {
+            return nullptr;
+        }
+        pos += argumentStart;
+        CSSFunctionValue* transformValue = CSSFunctionValue::create(transformType);
+        if (!parseTransformRotateArguments(pos, end, transformValue))
+            return nullptr;
+        return transformValue;
+    }
+
     return nullptr;
 }