Pass zone explicitly to zone-allocation on x64 and ARM.

src/ia32/lithium-ia32.h

Index: src/ia32/lithium-ia32.h
===================================================================
--- src/ia32/lithium-ia32.h	(revision 10852)
+++ src/ia32/lithium-ia32.h	(working copy)
@@ -2321,7 +2321,7 @@
       : chunk_(NULL),
         info_(info),
         graph_(graph),
-        isolate_(graph->isolate()),
+        zone_(graph->isolate()->zone()),
         status_(UNUSED),
         current_instruction_(NULL),
         current_block_(NULL),
@@ -2351,7 +2351,7 @@
   LChunk* chunk() const { return chunk_; }
   CompilationInfo* info() const { return info_; }
   HGraph* graph() const { return graph_; }
-  Zone* zone() { return isolate_->zone(); }
+  Zone* zone() { return zone_; }
 
   bool is_unused() const { return status_ == UNUSED; }
   bool is_building() const { return status_ == BUILDING; }
@@ -2460,7 +2460,7 @@
   LChunk* chunk_;
   CompilationInfo* info_;
   HGraph* const graph_;
-  Isolate* isolate_;
+  Zone* zone_;
   Status status_;
   HInstruction* current_instruction_;
   HBasicBlock* current_block_;