Specialize breakpoint stubs by set of live registers of the stubs they are intercepting.

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 ddd63cb7c865100bc3ccb43111f41ec0e93c45ab..118093e7488355d427d32bc86987c3242387c6ff 100644
--- a/runtime/vm/flow_graph_compiler_arm.cc
+++ b/runtime/vm/flow_graph_compiler_arm.cc
@@ -1215,7 +1215,6 @@ void FlowGraphCompiler::EmitInstanceCall(ExternalLabel* target_label,
                                          intptr_t token_pos,
                                          LocationSummary* locs) {
   ASSERT(Array::Handle(ic_data.arguments_descriptor()).Length() > 0);
-  __ LoadImmediate(R4, 0);
   __ LoadObject(R5, ic_data);
   GenerateDartCall(deopt_id,
                    token_pos,
@@ -1307,7 +1306,6 @@ void FlowGraphCompiler::EmitUnoptimizedStaticCall(
     UNIMPLEMENTED();
   }
   ExternalLabel target_label(label_address);
-  __ LoadImmediate(R4, 0);
   __ LoadObject(R5, ic_data);
   GenerateDartCall(deopt_id,
                    token_pos,
@@ -1317,6 +1315,7 @@ void FlowGraphCompiler::EmitUnoptimizedStaticCall(
   __ Drop(argument_count);
 #if defined(DEBUG)
   __ LoadImmediate(R4, kInvalidObjectPointer);
+  __ LoadImmediate(R5, kInvalidObjectPointer);
 #endif
 }
 
@@ -1384,8 +1383,6 @@ void FlowGraphCompiler::EmitEqualityRegRegCompare(Register left,
       __ BranchLinkPatchable(
           &stub_code->OptimizedIdenticalWithNumberCheckLabel());
     } else {
-      __ LoadImmediate(R4, 0);
-      __ LoadImmediate(R5, 0);
       __ BranchLinkPatchable(
           &stub_code->UnoptimizedIdenticalWithNumberCheckLabel());
     }