Make array allocation stub shared between isolates.

runtime/vm/debugger_arm.cc

Index: runtime/vm/debugger_arm.cc
diff --git a/runtime/vm/debugger_arm.cc b/runtime/vm/debugger_arm.cc
index e84ffa91712583818d0ec1e13673ad0fb1d4b695..c642d94d270b02164cb62d9af20d0f54bbe32c27 100644
--- a/runtime/vm/debugger_arm.cc
+++ b/runtime/vm/debugger_arm.cc
@@ -20,15 +20,14 @@ uword CodeBreakpoint::OrigStubAddress() const {
 
 void CodeBreakpoint::PatchCode() {
   ASSERT(!is_enabled_);
-  StubCode* stub_code = Isolate::Current()->stub_code();
   uword stub_target = 0;
   switch (breakpoint_kind_) {
     case RawPcDescriptors::kIcCall:
     case RawPcDescriptors::kUnoptStaticCall:
-      stub_target = stub_code->ICCallBreakpointEntryPoint();
+      stub_target = StubCode::ICCallBreakpointEntryPoint();
       break;
     case RawPcDescriptors::kRuntimeCall:
-      stub_target = stub_code->RuntimeCallBreakpointEntryPoint();
+      stub_target = StubCode::RuntimeCallBreakpointEntryPoint();
       break;
     default:
       UNREACHABLE();