Introduce 'trivial' expressions, use them for this property assignments.

src/ia32/virtual-frame-ia32.h

Index: src/ia32/virtual-frame-ia32.h
diff --git a/src/ia32/virtual-frame-ia32.h b/src/ia32/virtual-frame-ia32.h
index b078ba0897444c57fb63a7b0d265d9050ba09201..59142b40e2834d4100ce4a034eb330dbf59cc992 100644
--- a/src/ia32/virtual-frame-ia32.h
+++ b/src/ia32/virtual-frame-ia32.h
@@ -415,6 +415,10 @@ class VirtualFrame: public ZoneObject {
     result->Unuse();
   }
 
+  // Pushing an expression expects that the expression is trivial (according
+  // to Expression::IsTrivial).
+  void Push(Expression* expr);
+
   // Nip removes zero or more elements from immediately below the top
   // of the frame, leaving the previous top-of-frame value on top of
   // the frame.  Nip(k) is equivalent to x = Pop(), Drop(k), Push(x).