Reland of "Release streamed script resources after it was compiled"

src/background-parsing-task.h

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_BACKGROUND_PARSING_TASK_H_
 #define V8_BACKGROUND_PARSING_TASK_H_
 
 #include <memory>
 
 #include "src/base/platform/platform.h"
 #include "src/base/platform/semaphore.h"
 #include "src/compiler.h"
 #include "src/parsing/parse-info.h"
 #include "src/parsing/parser.h"
 
 namespace v8 {
 namespace internal {
 
 class ScriptData;
 
 // Internal representation of v8::ScriptCompiler::StreamedSource. Contains all
 // data which needs to be transmitted between threads for background parsing,
 // finalizing it on the main thread, and compiling on the main thread.
 struct StreamedSource {
   StreamedSource(ScriptCompiler::ExternalSourceStream* source_stream,
                  ScriptCompiler::StreamedSource::Encoding encoding)
       : source_stream(source_stream), encoding(encoding) {}
 
+  void Release() {
+    parser.reset();
+    info.reset();
+    zone.reset();
+  }
+
   // Internal implementation of v8::ScriptCompiler::StreamedSource.
   std::unique_ptr<ScriptCompiler::ExternalSourceStream> source_stream;
   ScriptCompiler::StreamedSource::Encoding encoding;
   std::unique_ptr<ScriptCompiler::CachedData> cached_data;
 
   // Data needed for parsing, and data needed to to be passed between thread
   // between parsing and compilation. These need to be initialized before the
   // compilation starts.
   UnicodeCache unicode_cache;
   std::unique_ptr<Zone> zone;
@@ skipping 16 matching lines @@
 
  private:
   StreamedSource* source_;  // Not owned.
   int stack_size_;
   ScriptData* script_data_;
 };
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_BACKGROUND_PARSING_TASK_H_