Faster IC stubs by specializing them for Binary Smi operations

runtime/vm/object.h

Index: runtime/vm/object.h
===================================================================
--- runtime/vm/object.h	(revision 39307)
+++ runtime/vm/object.h	(working copy)
@@ -3505,6 +3505,13 @@
   bool HasOneTarget() const;
   bool HasReceiverClassId(intptr_t class_id) const;
 
+  // Returns true if some entries have count 0, except if the ICData is used
+  // by an unoptimized static call.
+  bool HasUnusedEntries() const;
+
+  // Returns a new ICData with all unused entries removed.
+  RawICData* FilterUnusedEntries() const;
+
   static RawICData* New(const Function& owner,
                         const String& target_name,
                         const Array& arguments_descriptor,