Precompilation: Generate instance calls as IC calls that can switch to Megamoprhic calls.

runtime/vm/instructions_arm64.h

Index: runtime/vm/instructions_arm64.h
diff --git a/runtime/vm/instructions_arm64.h b/runtime/vm/instructions_arm64.h
index 0d2c96d70ceba0d775b65f631bd78f6504fa8c63..6195d52b5942ed825a22fc1064e91dd669e4e63c 100644
--- a/runtime/vm/instructions_arm64.h
+++ b/runtime/vm/instructions_arm64.h
@@ -106,6 +106,27 @@ class NativeCallPattern : public ValueObject {
 };
 
 
+// Instance call that can switch from an IC call to a megamorphic call
+//   load ICData             load MegamorphicCache
+//   call ICLookup stub  ->  call MegamorphicLookup stub
+//   call target             call target
+class SwitchableCallPattern : public ValueObject {
+ public:
+  SwitchableCallPattern(uword pc, const Code& code);
+
+  RawObject* cache() const;
+  void SetCache(const MegamorphicCache& cache) const;
+  void SetLookupStub(const Code& stub) const;
+
+ private:
+  const ObjectPool& object_pool_;
+  intptr_t cache_pool_index_;
+  intptr_t stub_pool_index_;
+
+  DISALLOW_COPY_AND_ASSIGN(SwitchableCallPattern);
+};
+
+
 class ReturnPattern : public ValueObject {
  public:
   explicit ReturnPattern(uword pc);