Fix handling of inline JS types in DDC.

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

Index: pkg/dev_compiler/tool/input_sdk/private/ddc_runtime/classes.dart
diff --git a/pkg/dev_compiler/tool/input_sdk/private/ddc_runtime/classes.dart b/pkg/dev_compiler/tool/input_sdk/private/ddc_runtime/classes.dart
index 63c95c4272f16297b2e622c1bb93a5278e981f17..779eb3979ab16f886583d18c2754f8a37b17e626 100644
--- a/pkg/dev_compiler/tool/input_sdk/private/ddc_runtime/classes.dart
+++ b/pkg/dev_compiler/tool/input_sdk/private/ddc_runtime/classes.dart
@@ -376,18 +376,18 @@ setSignature(f, signature) => JS(
   $_setStaticTypes($f, names);
 })()''');
 
-_hasSigEntry(type, sigF, name) => JS(
-    '',
+bool _hasSigEntry(type, sigF, name) => JS(
+    'bool',
     '''(() => {
   let sigObj = $type[$sigF];
   if (sigObj === void 0) return false;
   return $name in sigObj;
 })()''');
 
-hasMethod(type, name) => _hasSigEntry(type, _methodSig, name);
-hasGetter(type, name) => _hasSigEntry(type, _getterSig, name);
-hasSetter(type, name) => _hasSigEntry(type, _setterSig, name);
-hasField(type, name) => _hasSigEntry(type, _fieldSig, name);
+bool hasMethod(type, name) => _hasSigEntry(type, _methodSig, name);
+bool hasGetter(type, name) => _hasSigEntry(type, _getterSig, name);
+bool hasSetter(type, name) => _hasSigEntry(type, _setterSig, name);
+bool hasField(type, name) => _hasSigEntry(type, _fieldSig, name);
 
 final _extensionType = JS('', 'Symbol("extensionType")');