[Turbofan] Add concept of FP register aliasing on ARM 32.

src/zone/zone-allocator.h

Index: src/zone/zone-allocator.h
diff --git a/src/zone/zone-allocator.h b/src/zone/zone-allocator.h
index 8370d73e49b2fc1337162410fe39011512a6baf1..1e2862a2c1144b018884d6c55643f301c6bff3be 100644
--- a/src/zone/zone-allocator.h
+++ b/src/zone/zone-allocator.h
@@ -26,6 +26,8 @@ class zone_allocator {
     typedef zone_allocator<O> other;
   };
 
+  // TODO(bbudge) Remove when V8 updates to MSVS 2015. See crbug.com/603131.
+  zone_allocator() : zone_(nullptr) { UNREACHABLE(); }
   explicit zone_allocator(Zone* zone) throw() : zone_(zone) {}
   explicit zone_allocator(const zone_allocator& other) throw()
       : zone_(other.zone_) {}
@@ -62,7 +64,6 @@ class zone_allocator {
   Zone* zone() { return zone_; }
 
  private:
-  zone_allocator();
   Zone* zone_;
 };