simplify emitting dart.bind for native types

R=het@google.com

Review URL: https://codereview.chromium.org/1921503007 .

pkg/dev_compiler/lib/runtime/dart_sdk.js

@@ -114,9 +114,8 @@ dart_library.library('dart_sdk', null, /* Imports */[
   dart._methodSig = Symbol("sig");
   dart._staticSig = Symbol("sigStatic");
   dart.getMethodType = function(obj, name) {
-    if (obj === void 0) return void 0;
-    if (obj == null) return void 0;
-    return dart.getMethodTypeFromType(obj.__proto__.constructor, name);
+    let type = obj == null ? core.Object : obj.__proto__.constructor;
+    return dart.getMethodTypeFromType(type, name);
   };
   dart.getMethodTypeFromType = function(type, name) {
     let sigObj = type[dart._methodSig];

pkg/dev_compiler/lib/src/compiler/code_generator.dart

@@ -2284,7 +2284,7 @@ class CodeGenerator extends GeneralizingAstVisitor
       //     class Foo { Function bar; }
       //     new Foo().bar(); // dynamic call
       code = 'dart.dcall(#.#, #)';
-    } else if (_requiresStaticDispatch(target, name)) {
+    } else if (_isObjectMemberCall(target, name)) {
       // Object methods require a helper for null checks.
       return js.call('dart.#(#, #)',
           [memberName, _visit(target), _visit(node.argumentList)]);
@@ -3129,15 +3129,21 @@ class CodeGenerator extends GeneralizingAstVisitor
     }
   }
 
-  bool _requiresStaticDispatch(Expression target, String memberName) {
-    var type = getStaticType(target);
+  /// Everything in Dart is an Object and supports the 4 members on Object,
+  /// so we have to use a runtime helper to handle values such as `null` and
+  /// native types.
+  ///
+  /// For example `null.toString()` is legal in Dart, so we need to generate
+  /// that as `dart.toString(obj)`.
+  bool _isObjectMemberCall(Expression target, String memberName) {
+    // Is this a member on `Object`?
     if (!isObjectProperty(memberName)) {
       return false;
     }
 
-    // If the target could be `null`, we need static dispatch.
-    // If the target may be an extension type, we also use static dispatch
-    // as we don't symbolize object properties like hashCode.
+    // Check if the target could be `null`, is dynamic, or may be an extension
+    // native type. In all of those cases we need defensive code generation.
+    var type = getStaticType(target);
     return isNullable(target) ||
         type.isDynamic ||
         (_extensionTypes.contains(type.element) && target is! SuperExpression);
@@ -3169,13 +3175,11 @@ class CodeGenerator extends GeneralizingAstVisitor
       // Tear-off methods: explicitly bind it.
       if (target is SuperExpression) {
         return js.call('dart.bind(this, #, #.#)', [name, _visit(target), name]);
-      } else if (_requiresStaticDispatch(target, memberId.name)) {
-        var type = member.type;
-        var clos = js.call('dart.#.bind(#)', [name, _visit(target)]);
-        return js.call('dart.fn(#, #)', [clos, _emitFunctionTypeParts(type)]);
+      } else if (_isObjectMemberCall(target, memberId.name)) {
+        return js.call('dart.bind(#, #, dart.#)', [_visit(target), name, name]);
       }
       code = 'dart.bind(#, #)';
-    } else if (_requiresStaticDispatch(target, memberId.name)) {
+    } else if (_isObjectMemberCall(target, memberId.name)) {
       return js.call('dart.#(#)', [name, _visit(target)]);
     } else {
       code = '#.#';

pkg/dev_compiler/test/codegen/expect/language-all.js

@@ -117604,7 +117604,7 @@ dart_library.library('null_to_string2_test', null, /* Imports */[
     let nullObj = null_to_string2_test.foo();
     let x = dart.toString(nullObj);
     expect$.Expect.isTrue(typeof x == 'string');
-    let y = dart.fn(dart.toString.bind(nullObj), core.String, []);
+    let y = dart.bind(nullObj, 'toString', dart.toString);
     expect$.Expect.isNotNull(y);
   };
   dart.fn(null_to_string2_test.main);

pkg/dev_compiler/tool/input_sdk/private/ddc_runtime/classes.dart

@@ -124,9 +124,8 @@ final _staticSig = JS('', 'Symbol("sigStatic")');
 
 /// Get the type of a method from an object using the stored signature
 getMethodType(obj, name) => JS('', '''(() => {
-  if ($obj === void 0) return void 0;
-  if ($obj == null) return void 0;
-  return $getMethodTypeFromType($obj.__proto__.constructor, $name);
+  let type = $obj == null ? $Object : $obj.__proto__.constructor;
+  return $getMethodTypeFromType(type, $name);
 })()''');
 
 /// Get the type of a method from a type using the stored signature