Implement bookmarks for ExternalStreamingStream.

include/v8.h

Index: include/v8.h
diff --git a/include/v8.h b/include/v8.h
index 483699cbda9da065ae12000019af1f1f33eaeb00..b3d7af13cc9d2bf5a507fe8cb0cdda9d5e71e090 100644
--- a/include/v8.h
+++ b/include/v8.h
@@ -1222,6 +1222,23 @@ class V8_EXPORT ScriptCompiler {
      * V8 has parsed the data it received so far.
      */
     virtual size_t GetMoreData(const uint8_t** src) = 0;
+
+    /**
+     * V8 calls this method to set a 'bookmark' at the current position in
+     * the source stream, for the purpose of (maybe) later calling
+     * ResetToBookmark. If ResetToBookmark is called later, then subsequent
+     * calls to GetMoreData should return the same data as they did when
+     * SetBookmark was called earlier.
+     *
+     * The embedder may return 'false' to indicate it cannot provide this
+     * functionality.
+     */
+    virtual bool SetBookmark();
+
+    /**
+     * V8 calls this to return to a previously set bookmark.
+     */
+    virtual void ResetToBookmark();
   };