Cleanup: Replace LoadInstanceFieldInstr with LoadVMFieldInstr.

runtime/vm/intermediate_language_x64.cc

Index: runtime/vm/intermediate_language_x64.cc
===================================================================
--- runtime/vm/intermediate_language_x64.cc	(revision 12267)
+++ runtime/vm/intermediate_language_x64.cc	(working copy)
@@ -966,24 +966,6 @@
 }
 
 
-LocationSummary* LoadInstanceFieldInstr::MakeLocationSummary() const {
-  // TODO(fschneider): For this instruction the input register may be
-  // reused for the result (but is not required to) because the input
-  // is not used after the result is defined.  We should consider adding
-  // this information to the input policy.
-  return LocationSummary::Make(1,
-                               Location::RequiresRegister(),
-                               LocationSummary::kNoCall);
-}
-
-
-void LoadInstanceFieldInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
-  Register instance_reg = locs()->in(0).reg();
-  Register result_reg = locs()->out().reg();
-  __ movq(result_reg, FieldAddress(instance_reg, field().Offset()));
-}
-
-
 LocationSummary* StoreInstanceFieldInstr::MakeLocationSummary() const {
   const intptr_t kNumInputs = 2;
   const intptr_t num_temps = 0;