Reduce space used for stackmaps.

runtime/vm/flow_graph_compiler.cc

Index: runtime/vm/flow_graph_compiler.cc
diff --git a/runtime/vm/flow_graph_compiler.cc b/runtime/vm/flow_graph_compiler.cc
index 28b4a649502b0a875866fe37351f599d16bf778b..ebfde00c1d249c1b7a0f87e8aaa4553e76e40e8f 100644
--- a/runtime/vm/flow_graph_compiler.cc
+++ b/runtime/vm/flow_graph_compiler.cc
@@ -87,7 +87,7 @@ FlowGraphCompiler::FlowGraphCompiler(
       current_block_(NULL),
       exception_handlers_list_(NULL),
       pc_descriptors_list_(NULL),
-      stackmap_table_builder_(is_ssa ? new StackmapTableBuilder() : NULL),
+      stackmap_table_builder_(NULL),
       block_info_(block_order.length()),
       deopt_stubs_(),
       object_table_(GrowableObjectArray::Handle(GrowableObjectArray::New())),
@@ -102,6 +102,9 @@ FlowGraphCompiler::FlowGraphCompiler(
       parallel_move_resolver_(this) {
   ASSERT(assembler != NULL);
   ASSERT(is_optimizing_ || !is_ssa_);
+  if (is_ssa_) {
+    stackmap_table_builder_ = new StackmapTableBuilder(StackSize());
+  }
 }