Get rid of deprecated methods accessing mutator_thread_ instead of current thread

runtime/vm/dart_api_impl.h

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef VM_DART_API_IMPL_H_
 #define VM_DART_API_IMPL_H_
 
 #include "vm/allocation.h"
 #include "vm/native_arguments.h"
 #include "vm/object.h"
@@ skipping 94 matching lines @@
           CURRENT_FUNC, #length, max);                                         \
     }                                                                          \
   } while (0)
 
 
 class Api : AllStatic {
  public:
   // Create on the stack to provide a new throw-safe api scope.
   class Scope : public StackResource {
    public:
-    explicit Scope(Isolate* isolate) : StackResource(isolate) {
+    explicit Scope(Thread* thread) : StackResource(thread) {
       Dart_EnterScope();
     }
     ~Scope() {
       Dart_ExitScope();
     }
 
    private:
     DISALLOW_COPY_AND_ASSIGN(Scope);
   };
 
@@ skipping 196 matching lines @@
     return Api::NewError("%s: Cannot load after Dart_Precompile",              \
                          CURRENT_FUNC);                                        \
   }                                                                            \
 
 #define ASSERT_CALLBACK_STATE(thread)                                         \
   ASSERT(thread->no_callback_scope_depth() == 0)
 
 }  // namespace dart.
 
 #endif  // VM_DART_API_IMPL_H_