Two-threaded parser

src/parser.h

Index: src/parser.h
diff --git a/src/parser.h b/src/parser.h
index 4f872a6e0d257429b0088454179ccc452bc315c3..58770efaf961c34851c04493cf4679147fa589f3 100644
--- a/src/parser.h
+++ b/src/parser.h
@@ -766,10 +766,15 @@ class Parser : public ParserBase<ParserTraits> {
   // Skip over a lazy function, either using cached data if we have it, or
   // by parsing the function with PreParser. Consumes the ending }.
   void SkipLazyFunctionBody(Handle<String> function_name,
+                            int function_block_pos,
                             int* materialized_literal_count,
                             int* expected_property_count,
+                            StrictMode* strict_mode,
                             bool* ok);
 
+  void ProcessErrorFromRecorder(PreParser::PreParseResult result,
+                                const SingletonLogger* logger, bool* ok);
+
   PreParser::PreParseResult ParseLazyFunctionBodyWithPreParser(
       SingletonLogger* logger);
 
@@ -781,6 +786,17 @@ class Parser : public ParserBase<ParserTraits> {
                                                bool is_generator,
                                                bool* ok);
 
+  // If possible, starts a background task for doing a fast pass over the script
+  // to find lazy functions with PreParser. Restrictions: 1) PreParser cannot
+  // yet parse everything that Parser can (e.g., harmony modules). So here we
+  // are on the safe side, and only use the FastParserThread when we're sure
+  // that the script is good (i.e., for scripts for which we produce cached
+  // data). TODO(marja): Use background tasks for other kinds of compilations
+  // too. 2) The thread cannot use the Isolate, or Handles, so this will only
+  // work if the actual data is kept outside the V8 heap as an external string.
+  void StartFastParserTaskIfPossible(Handle<String> source);
+  void FinishFastParserTask();
+
   Isolate* isolate_;
 
   Handle<Script> script_;