Make blink::protocol::StringBuilder a distinct type from WTF::StringBuilder.

third_party/WebKit/Source/core/inspector/V8InspectorString.h

Index: third_party/WebKit/Source/core/inspector/V8InspectorString.h
diff --git a/third_party/WebKit/Source/core/inspector/V8InspectorString.h b/third_party/WebKit/Source/core/inspector/V8InspectorString.h
index bb2274e9e11f2aa677ec270cbfdfb04d5de713e6..27bde22cdfc5fad7556998d01e51be086a182b97 100644
--- a/third_party/WebKit/Source/core/inspector/V8InspectorString.h
+++ b/third_party/WebKit/Source/core/inspector/V8InspectorString.h
@@ -46,9 +46,21 @@ class CORE_EXPORT StringUtil {
     return Decimal::fromDouble(number).toString();
   }
   static const size_t kNotFound = WTF::kNotFound;
+  static void builderAppend(StringBuilder& builder, const String& s) {
+    builder.append(s);
+  }
+  static void builderAppend(StringBuilder& builder, UChar c) {
+    builder.append(c);
+  }
+  static void builderAppend(StringBuilder& builder, const char* s, size_t len) {
+    builder.append(s, len);
+  }
   static void builderReserve(StringBuilder& builder, unsigned capacity) {
     builder.reserveCapacity(capacity);
   }
+  static String builderToString(StringBuilder& builder) {
+    return builder.toString();
+  }
   static std::unique_ptr<protocol::Value> parseJSON(const String&);
 };