VM: Move representation selection code out of the flow graph optimizer.

runtime/vm/flow_graph_compiler_arm.cc

Index: runtime/vm/flow_graph_compiler_arm.cc
diff --git a/runtime/vm/flow_graph_compiler_arm.cc b/runtime/vm/flow_graph_compiler_arm.cc
index 4eb7f3f69cfded927edf6bef76faf5966e19fd2a..2b1454502b9595bb9d4758ebdce0dd94c5780c2a 100644
--- a/runtime/vm/flow_graph_compiler_arm.cc
+++ b/runtime/vm/flow_graph_compiler_arm.cc
@@ -78,6 +78,13 @@ bool FlowGraphCompiler::SupportsHardwareDivision() {
 }
 
 
+bool FlowGraphCompiler::CanConvertUnboxedMintToDouble() {
+  // ARM does not have a short instruction sequence for converting int64 to
+  // double.
+  return false;
+}
+
+
 void FlowGraphCompiler::EnterIntrinsicMode() {
   ASSERT(!intrinsic_mode());
   intrinsic_mode_ = true;