RegExp: Add support for the ES6-proposed sticky flag

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index 32dd94f39b64457b6cbe853647222c22d49ba8e5..810cd1772140b68e3cfecaedc0ef0a7d3052b4f4 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -8031,7 +8031,13 @@ class JSRegExp: public JSObject {
   // IRREGEXP: Compiled with Irregexp.
   // IRREGEXP_NATIVE: Compiled to native code with Irregexp.
   enum Type { NOT_COMPILED, ATOM, IRREGEXP };
-  enum Flag { NONE = 0, GLOBAL = 1, IGNORE_CASE = 2, MULTILINE = 4 };
+  enum Flag {
+    NONE = 0,
+    GLOBAL = 1,
+    IGNORE_CASE = 2,
+    MULTILINE = 4,
+    STICKY = 8
+  };
 
   class Flags {
    public:
@@ -8039,6 +8045,7 @@ class JSRegExp: public JSObject {
     bool is_global() { return (value_ & GLOBAL) != 0; }
     bool is_ignore_case() { return (value_ & IGNORE_CASE) != 0; }
     bool is_multiline() { return (value_ & MULTILINE) != 0; }
+    bool is_sticky() { return (value_ & STICKY) != 0; }
     uint32_t value() { return value_; }
    private:
     uint32_t value_;