Add script streaming API

src/isolate.h

Index: src/isolate.h
diff --git a/src/isolate.h b/src/isolate.h
index 9ef6fc732a9f9f64c22fd4449ce28834a0107083..428e6f06411ac7da89c39306d9c1ad2e27878090 100644
--- a/src/isolate.h
+++ b/src/isolate.h
@@ -32,6 +32,7 @@ class RandomNumberGenerator;
 
 namespace internal {
 
+class BackgroundParserThread;
 class Bootstrapper;
 class CallInterfaceDescriptor;
 class CodeGenerator;
@@ -1055,6 +1056,10 @@ class Isolate {
     return optimizing_compiler_thread_;
   }
 
+  BackgroundParserThread* background_parser_thread() {
+    return background_parser_thread_;
+  }
+
   int num_sweeper_threads() const {
     return num_sweeper_threads_;
   }
@@ -1313,6 +1318,7 @@ class Isolate {
 
   DeferredHandles* deferred_handles_head_;
   OptimizingCompilerThread* optimizing_compiler_thread_;
+  BackgroundParserThread* background_parser_thread_;
   SweeperThread** sweeper_thread_;
   int num_sweeper_threads_;