[Ignition/turbo] Add a NewWithSpread bytecode.

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index df61275d9b17d4f78e814ab50736c10502247be3..02dbc4539ed02022679fde2c51d47073ad5f08e5 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -1505,6 +1505,11 @@ class Object {
   // allow kMaxUInt32.
   inline bool ToArrayIndex(uint32_t* index);
 
+  // Returns true if the result of iterating over the object is the same
+  // (including observable effects) as simply accessing the properties between 0
+  // and length.
+  bool MustIterate();

[Benedikt Meurer, 2016/12/05 11:42:10]

Nit: This should have a more scary^Wdescriptive name like
CanUseElementsInsteadOfIteration() or something like that.

[petermarshall, 2016/12/05 13:30:46]

Done

+
   DECLARE_VERIFIER(Object)
 #ifdef VERIFY_HEAP
   // Verify a pointer is a valid object pointer.