dart2js: Make usage of names more consistent between compiler and runtime.

tests/compiler/dart2js/deferred_emit_type_checks_test.dart

Index: tests/compiler/dart2js/deferred_emit_type_checks_test.dart
diff --git a/tests/compiler/dart2js/deferred_emit_type_checks_test.dart b/tests/compiler/dart2js/deferred_emit_type_checks_test.dart
index 6ece06e02d56ffc9fb5ef80c7d8f26e60b807953..d397ababc0fb6e613034f3ea24123b1439db7d65 100644
--- a/tests/compiler/dart2js/deferred_emit_type_checks_test.dart
+++ b/tests/compiler/dart2js/deferred_emit_type_checks_test.dart
@@ -52,8 +52,10 @@ void main() {
   asyncTest(() => compiler.run(Uri.parse('memory:main.dart')).then((_) {
     String mainOutput = outputs['main.js'].mem[0];
     String deferredOutput = outputs['out_1.part.js'].mem[0];
-    RegExp re = new RegExp(r"\n  _ = .\.A;\n  _.\$isA = TRUE;");
-    print(deferredOutput);
+    String isPrefix = compiler.backend.namer.operatorIsPrefix;
+    String escapedIsPrefix = isPrefix.replaceAll(r'$', r'\$');
+    RegExp re = new RegExp(r"\n  _ = .\.A;\n  _."
+                            "${escapedIsPrefix}A = TRUE;");
     Expect.isTrue(re.hasMatch(deferredOutput));
     Expect.isFalse(re.hasMatch(mainOutput));
   }));