Remove HType::HeapNumber from mutable heap numbers.

src/hydrogen-instructions.h

Index: src/hydrogen-instructions.h
diff --git a/src/hydrogen-instructions.h b/src/hydrogen-instructions.h
index 4f83aafa72e0515cf4a419f1d1cc16f25ba29a81..0ecad2369ae14982a98c13f6f4548d54e7895943 100644
--- a/src/hydrogen-instructions.h
+++ b/src/hydrogen-instructions.h
@@ -714,7 +714,6 @@ class HValue : public ZoneObject {
     if (r.IsTagged()) {
       HType t = type();
       if (t.IsSmi()) return Representation::Smi();
-      // TODO(mstarzinger): This is not correct for mutable HeapNumbers.
       if (t.IsHeapNumber()) return Representation::Double();
       if (t.IsHeapObject()) return r;
       return Representation::None();
@@ -5547,10 +5546,6 @@ class HAllocate V8_FINAL : public HTemplateInstruction<2> {
       return Representation::Integer32();
     }
   }
-  // TODO(mstarzinger): Workaround until we track mutable HeapNumber types.
-  virtual Representation KnownOptimalRepresentation() V8_OVERRIDE {
-    return representation();
-  }
 
   virtual Handle<Map> GetMonomorphicJSObjectMap() {
     return known_initial_map_;