[builtins] Add support for NewTarget to Execution::New.

src/globals.h

Index: src/globals.h
diff --git a/src/globals.h b/src/globals.h
index f69db94faefc3b36848e30067fc357c8a9e961d1..2b6987fda7feb7ccc180077875716d1ab9323672 100644
--- a/src/globals.h
+++ b/src/globals.h
@@ -601,6 +601,10 @@ enum CallConstructorFlags {
   NO_CALL_CONSTRUCTOR_FLAGS = 0,
   // The call target is cached in the instruction stream.
   RECORD_CONSTRUCTOR_TARGET = 1,
+  // TODO(bmeurer): Kill these SUPER_* modes and use the Construct builtin
+  // directly instead; also there's no point in collecting any "targets" for
+  // super constructor calls, since these are known when we optimize the
+  // constructor that contains the super call.
   SUPER_CONSTRUCTOR_CALL = 1 << 1,
   SUPER_CALL_RECORD_TARGET = SUPER_CONSTRUCTOR_CALL | RECORD_CONSTRUCTOR_TARGET
 };