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

src/background-parsing-task.h

Index: src/background-parsing-task.h
diff --git a/src/background-parsing-task.h b/src/background-parsing-task.h
index bd96ee1f857b46f5b736930b8a9d683342f3a998..afa2bff32b126473890b9e6f1b5e97afd2560046 100644
--- a/src/background-parsing-task.h
+++ b/src/background-parsing-task.h
@@ -26,6 +26,12 @@ struct StreamedSource {
                  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;