new classes: implement new.target passing to superclass constructor.

src/variables.h

Index: src/variables.h
diff --git a/src/variables.h b/src/variables.h
index 93bfb4a1816aeb3fb9f370c847ace86da6f2d6b3..e35ae7d1cc377f823cf57837574c00b1cf14f953 100644
--- a/src/variables.h
+++ b/src/variables.h
@@ -19,11 +19,7 @@ namespace internal {
 
 class Variable: public ZoneObject {
  public:
-  enum Kind {
-    NORMAL,
-    THIS,
-    ARGUMENTS
-  };
+  enum Kind { NORMAL, THIS, NEW_TARGET, ARGUMENTS };
 
   enum Location {
     // Before and during variable allocation, a variable whose location is
@@ -105,6 +101,7 @@ class Variable: public ZoneObject {
   }
 
   bool is_this() const { return kind_ == THIS; }
+  bool is_new_target() const { return kind_ == NEW_TARGET; }
   bool is_arguments() const { return kind_ == ARGUMENTS; }
 
   // True if the variable is named eval and not known to be shadowed.