Store pointer instead of reference to LocalVariable in ast and flow graph.

runtime/vm/intermediate_language_x64.cc

Index: runtime/vm/intermediate_language_x64.cc
===================================================================
--- runtime/vm/intermediate_language_x64.cc	(revision 10207)
+++ runtime/vm/intermediate_language_x64.cc	(working copy)
@@ -136,7 +136,7 @@
 
 void LoadLocalComp::EmitNativeCode(FlowGraphCompiler* compiler) {
   Register result = locs()->out().reg();
-  __ movq(result, Address(RBP, local().index() * kWordSize));
+  __ movq(result, Address(RBP, local()->index() * kWordSize));
 }
 
 
@@ -151,7 +151,7 @@
   Register value = locs()->in(0).reg();
   Register result = locs()->out().reg();
   ASSERT(result == value);  // Assert that register assignment is correct.
-  __ movq(Address(RBP, local().index() * kWordSize), value);
+  __ movq(Address(RBP, local()->index() * kWordSize), value);
 }
 
 
@@ -1475,11 +1475,11 @@
       -locals_space_size + FlowGraphCompiler::kLocalsOffsetFromFP;
   __ leaq(RSP, Address(RBP, offset_size));
 
-  ASSERT(!exception_var().is_captured());
-  ASSERT(!stacktrace_var().is_captured());
-  __ movq(Address(RBP, exception_var().index() * kWordSize),
+  ASSERT(!exception_var()->is_captured());
+  ASSERT(!stacktrace_var()->is_captured());
+  __ movq(Address(RBP, exception_var()->index() * kWordSize),
           kExceptionObjectReg);
-  __ movq(Address(RBP, stacktrace_var().index() * kWordSize),
+  __ movq(Address(RBP, stacktrace_var()->index() * kWordSize),
           kStackTraceObjectReg);
 }