anchor.diff:        : directLocals = new Map<Local, HInstruction>.from(other.directLocals),
           redirectionMapping = other.redirectionMapping,
           executableContext = other.executableContext,
  +        instanceType = other.instanceType,
           builder = other.builder,
           closureData = other.closureData;
   
  
positive.code:     pushInvokeStatic(node,
                       backend.getRuntimeTypeToString(),
                       [value],
                       backend.stringType);
      pushInvokeStatic(node,
                       backend.getCreateRuntimeType(),
                       [pop()]);
  
negative.code:         compiler.internalError(node,
              'Isolate library and compiler mismatch.');
        }
        pushInvokeStatic(null, element, [], typeMask: backend.dynamicType);
      }
    }
  
  