[turbofan] Add support for transitioning stores to double fields.

src/interface-descriptors.h

Index: src/interface-descriptors.h
diff --git a/src/interface-descriptors.h b/src/interface-descriptors.h
index 42dca2eba727cfb0f3694f77f4172a343ef223d0..ceb6b69b9092e605f4b0d51513533c57acd2d36f 100644
--- a/src/interface-descriptors.h
+++ b/src/interface-descriptors.h
@@ -42,6 +42,7 @@ class PlatformInterfaceDescriptor;
   V(RegExpConstructResult)                    \
   V(TransitionElementsKind)                   \
   V(AllocateHeapNumber)                       \
+  V(AllocateMutableHeapNumber)                \
   V(AllocateInNewSpace)                       \
   V(ArrayConstructorConstantArgCount)         \
   V(ArrayConstructor)                         \
@@ -521,6 +522,13 @@ class AllocateHeapNumberDescriptor : public CallInterfaceDescriptor {
 };
 
 
+class AllocateMutableHeapNumberDescriptor : public CallInterfaceDescriptor {
+ public:
+  DECLARE_DESCRIPTOR(AllocateMutableHeapNumberDescriptor,
+                     CallInterfaceDescriptor)
+};
+
+
 class AllocateInNewSpaceDescriptor : public CallInterfaceDescriptor {
  public:
   DECLARE_DESCRIPTOR(AllocateInNewSpaceDescriptor, CallInterfaceDescriptor)