fix #30108, mock support for callable classes

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

Index: pkg/dev_compiler/lib/src/compiler/code_generator.dart
diff --git a/pkg/dev_compiler/lib/src/compiler/code_generator.dart b/pkg/dev_compiler/lib/src/compiler/code_generator.dart
index 75535faa7df093f1237ef6cac8eba245a83acf35..10c1659f81581c83c0dec373214bfd3401552acd 100644
--- a/pkg/dev_compiler/lib/src/compiler/code_generator.dart
+++ b/pkg/dev_compiler/lib/src/compiler/code_generator.dart
@@ -1838,8 +1838,12 @@ class CodeGenerator extends Object
     //
     // For the same reason, we can ignore "noSuchMethod".
     // call-implemented-by-nSM will be dispatched by dcall at runtime.

[vsm, 2017/07/14 14:19:56]

Remove or update the two lines above?

[Jennifer Messerly, 2017/07/14 18:40:20]

they're still accurate but i'll try and clarify:

    // We can ignore `noSuchMethod` because:
    // * `dynamic d; d();` without a declared `call` method is handled by dcall.
    // * for `class C implements Callable { noSuchMethod(i) { ... } }` we find
    //   the `call` method on the `Callable` interface.

-    bool isCallable = classElem.lookUpMethod('call', null) != null ||
-        classElem.lookUpGetter('call', null)?.returnType is FunctionType;
+    // For classes that implement a callable interface with nSM, we'll find
+    // the "call" when we search the type for inherited "call" members.
+    var callMethod = classElem.type.lookUpInheritedGetterOrMethod('call');
+    bool isCallable = callMethod is PropertyAccessorElement
+        ? callMethod.returnType is FunctionType
+        : callMethod != null;
 
     var body = <JS.Statement>[];
     void addConstructor(ConstructorElement element, JS.Expression jsCtor) {