Use symbol literals in the mirror tests. (Except for void, the empty string and setters.)

tests/lib/mirrors/function_type_mirror_test.dart

Index: tests/lib/mirrors/function_type_mirror_test.dart
diff --git a/tests/lib/mirrors/function_type_mirror_test.dart b/tests/lib/mirrors/function_type_mirror_test.dart
index 4376c83cf44240e139475be5c6c5cd4dcf31a7d1..f712d737e589ad46b7eeb9ca88d6d22d2c7f08af 100644
--- a/tests/lib/mirrors/function_type_mirror_test.dart
+++ b/tests/lib/mirrors/function_type_mirror_test.dart
@@ -13,11 +13,11 @@ bar(int a) {}
 main() {
   TypedefMirror tm = reflectClass(FooFunction);
   FunctionTypeMirror ftm = tm.referent;
-  Expect.equals(const Symbol("void"), ftm.returnType.simpleName);
-  Expect.equals(const Symbol("int"), ftm.parameters[0].type.simpleName);
-  Expect.equals(const Symbol("double"), ftm.parameters[1].type.simpleName);
+  Expect.equals(const Symbol('void'), ftm.returnType.simpleName);
+  Expect.equals(#int, ftm.parameters[0].type.simpleName);
+  Expect.equals(#double, ftm.parameters[1].type.simpleName);
   ClosureMirror cm = reflect(bar);
   ftm = cm.type;
-  Expect.equals(const Symbol("dynamic"), ftm.returnType.simpleName);
-  Expect.equals(const Symbol("int"), ftm.parameters[0].type.simpleName);
+  Expect.equals(#dynamic, ftm.returnType.simpleName);
+  Expect.equals(#int, ftm.parameters[0].type.simpleName);
 }