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 7a4b4d9c2a2d437cc9232650f73a7197fd0934da..ff23e5e169c39380618a98df9a5fd9e3b37f9684 100644
--- a/runtime/vm/flow_graph_compiler_arm.cc
+++ b/runtime/vm/flow_graph_compiler_arm.cc
@@ -1209,7 +1209,6 @@ 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,
@@ -1299,7 +1298,6 @@ void FlowGraphCompiler::EmitUnoptimizedStaticCall(
     UNIMPLEMENTED();
   }
   ExternalLabel target_label(label_address);
-  __ LoadImmediate(R4, 0);
   __ LoadObject(R5, ic_data);
   GenerateDartCall(deopt_id,
                    token_pos,
@@ -1373,8 +1371,6 @@ void FlowGraphCompiler::EmitEqualityRegRegCompare(Register left,
       __ BranchLinkPatchable(
           &StubCode::OptimizedIdenticalWithNumberCheckLabel());
     } else {
-      __ LoadImmediate(R4, 0);
-      __ LoadImmediate(R5, 0);
       __ BranchLinkPatchable(
           &StubCode::UnoptimizedIdenticalWithNumberCheckLabel());
     }