Backport r6579 (code generation bug on ARM).

src/arm/virtual-frame-arm.cc

Index: src/arm/virtual-frame-arm.cc
===================================================================
--- src/arm/virtual-frame-arm.cc	(revision 6597)
+++ src/arm/virtual-frame-arm.cc	(working copy)
@@ -68,6 +68,8 @@
 
 void VirtualFrame::MergeTo(const VirtualFrame* expected, Condition cond) {
   if (Equals(expected)) return;
+  ASSERT((expected->tos_known_smi_map_ & tos_known_smi_map_) ==
+         expected->tos_known_smi_map_);
   ASSERT(expected->IsCompatibleWith(this));
   MergeTOSTo(expected->top_of_stack_state_, cond);
   ASSERT(register_allocation_map_ == expected->register_allocation_map_);
@@ -76,7 +78,7 @@
 
 void VirtualFrame::MergeTo(VirtualFrame* expected, Condition cond) {
   if (Equals(expected)) return;
-  expected->tos_known_smi_map_ &= tos_known_smi_map_;
+  tos_known_smi_map_ &= expected->tos_known_smi_map_;
   MergeTOSTo(expected->top_of_stack_state_, cond);
   ASSERT(register_allocation_map_ == expected->register_allocation_map_);
 }