Refactored fast external string resource getter.

src/api.cc

Index: src/api.cc
diff --git a/src/api.cc b/src/api.cc
index 8b323b2f1fb7264f3b8da49cf1c491ec33c06742..dfe2de590cbe5c652622ae4c1664518adfe06152 100644
--- a/src/api.cc
+++ b/src/api.cc
@@ -4087,6 +4087,29 @@ void v8::String::VerifyExternalStringResource(
   CHECK_EQ(expected, value);
 }
 
+void v8::String::VerifyExternalStringResourceBase(
+    v8::String::ExternalStringResourceBase* value,
+    int type) const {
+  i::Handle<i::String> str = Utils::OpenHandle(this);
+  const v8::String::ExternalStringResourceBase* expected;
+  int expectedType;
+  if (i::StringShape(*str).IsExternalAscii()) {
+    const void* resource =
+        i::Handle<i::ExternalAsciiString>::cast(str)->resource();
+    expected = reinterpret_cast<const ExternalStringResourceBase*>(resource);
+    expectedType = kExternalAsciiStringType;
+  } else if (i::StringShape(*str).IsExternalTwoByte()) {
+    const void* resource =
+        i::Handle<i::ExternalTwoByteString>::cast(str)->resource();
+    expected = reinterpret_cast<const ExternalStringResourceBase*>(resource);
+    expectedType = kExternalTwoByteStringType;
+  } else {
+    expected = NULL;
+    expectedType = 0;
+  }
+  CHECK_EQ(expected, value);
+  CHECK_EQ(expectedType, type);
+}
 
 const v8::String::ExternalAsciiStringResource*
       v8::String::GetExternalAsciiStringResource() const {