Use signature inheritance when method types are unchanged

lib/runtime/dart/_foreign_helper.js

 var _foreign_helper = dart.defineLibrary(_foreign_helper, {});
 var core = dart.import(core);
 (function(exports, core) {
   'use strict';
   function JS(typeDescription, codeTemplate, arg0, arg1, arg2, arg3, arg4, arg5, arg6, arg7, arg8, arg9, arg10, arg11) {
     if (arg0 === void 0)
       arg0 = null;
     if (arg1 === void 0)
       arg1 = null;
     if (arg2 === void 0)
@@ skipping 15 matching lines @@
     if (arg10 === void 0)
       arg10 = null;
     if (arg11 === void 0)
       arg11 = null;
   }
   dart.fn(JS, dart.dynamic, [core.String, core.String], [dart.dynamic, dart.dynamic, dart.dynamic, dart.dynamic, dart.dynamic, dart.dynamic, dart.dynamic, dart.dynamic, dart.dynamic, dart.dynamic, dart.dynamic, dart.dynamic]);
   function JS_CURRENT_ISOLATE_CONTEXT() {
   }
   dart.fn(JS_CURRENT_ISOLATE_CONTEXT, () => dart.functionType(IsolateContext, []));
   class IsolateContext extends core.Object {}
-  dart.setSignature(IsolateContext, {});
   function JS_CALL_IN_ISOLATE(isolate, func) {
   }
   dart.fn(JS_CALL_IN_ISOLATE, dart.dynamic, [dart.dynamic, core.Function]);
   function DART_CLOSURE_TO_JS(func) {
   }
   dart.fn(DART_CLOSURE_TO_JS, dart.dynamic, [core.Function]);
   function RAW_DART_FUNCTION_REF(func) {
   }
   dart.fn(RAW_DART_FUNCTION_REF, dart.dynamic, [core.Function]);
   function JS_SET_CURRENT_ISOLATE(isolate) {
@@ skipping 64 matching lines @@
   dart.fn(JS_GET_FLAG, core.bool, [core.String]);
   function JS_EFFECT(code) {
     dart.dcall(code, null);
   }
   dart.fn(JS_EFFECT, dart.void, [core.Function]);
   class JS_CONST extends core.Object {
     JS_CONST(code) {
       this.code = code;
     }
   }
-  dart.setSignature(JS_CONST, {});
   function JS_STRING_CONCAT(a, b) {
     return a + b;
   }
   dart.fn(JS_STRING_CONCAT, core.String, [core.String, core.String]);
   // Exports:
   exports.JS = JS;
   exports.JS_CURRENT_ISOLATE_CONTEXT = JS_CURRENT_ISOLATE_CONTEXT;
   exports.IsolateContext = IsolateContext;
   exports.JS_CALL_IN_ISOLATE = JS_CALL_IN_ISOLATE;
   exports.DART_CLOSURE_TO_JS = DART_CLOSURE_TO_JS;
@@ skipping 17 matching lines @@
   exports.JS_FUNCTION_TYPE_REQUIRED_PARAMETERS_TAG = JS_FUNCTION_TYPE_REQUIRED_PARAMETERS_TAG;
   exports.JS_FUNCTION_TYPE_OPTIONAL_PARAMETERS_TAG = JS_FUNCTION_TYPE_OPTIONAL_PARAMETERS_TAG;
   exports.JS_FUNCTION_TYPE_NAMED_PARAMETERS_TAG = JS_FUNCTION_TYPE_NAMED_PARAMETERS_TAG;
   exports.JS_GET_NAME = JS_GET_NAME;
   exports.JS_EMBEDDED_GLOBAL = JS_EMBEDDED_GLOBAL;
   exports.JS_GET_FLAG = JS_GET_FLAG;
   exports.JS_EFFECT = JS_EFFECT;
   exports.JS_CONST = JS_CONST;
   exports.JS_STRING_CONCAT = JS_STRING_CONCAT;
 })(_foreign_helper, core);