Migrate most uses of StackZone(Isolate*) to Thread*.

runtime/vm/flow_graph.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/flow_graph.h"
 
 #include "vm/bit_vector.h"
 #include "vm/flow_graph_builder.h"
 #include "vm/il_printer.h"
 #include "vm/intermediate_language.h"
@@ skipping 167 matching lines @@
 
  private:
   BlockEntryInstr* block_;
   intptr_t next_successor_ix_;
 
   DISALLOW_ALLOCATION();
 };
 
 
 void FlowGraph::DiscoverBlocks() {
-  StackZone zone(isolate());
+  StackZone zone(thread());
 
   // Initialize state.
   preorder_.Clear();
   postorder_.Clear();
   reverse_postorder_.Clear();
   parent_.Clear();
 
   GrowableArray<BlockTraversalState> block_stack;
   graph_entry_->DiscoverBlock(NULL, &preorder_, &parent_);
   block_stack.Add(BlockTraversalState(graph_entry_));
@@ skipping 1191 matching lines @@
 }
 
 
 bool BlockEffects::IsSideEffectFreePath(BlockEntryInstr* from,
                                         BlockEntryInstr* to) const {
   return available_at_[to->postorder_number()]->Contains(
       from->postorder_number());
 }
 
 }  // namespace dart