Improve the stack trace output to be more readable.

vm/object_test.cc

Index: vm/object_test.cc
===================================================================
--- vm/object_test.cc	(revision 10396)
+++ vm/object_test.cc	(working copy)
@@ -2808,6 +2808,66 @@
 }
 
 
+TEST_CASE(StackTraceFormat) {
+  const char* kScriptChars =
+      "void baz() {\n"
+      "  throw 'MyException';\n"
+      "}\n"
+      "\n"
+      "class _OtherClass {\n"
+      "  _OtherClass._named() {\n"
+      "    baz();\n"
+      "  }\n"
+      "}\n"
+      "\n"
+      "set globalVar(var value) {\n"
+      "  new _OtherClass._named();\n"
+      "}\n"
+      "\n"
+      "void _bar() {\n"
+      "  globalVar = null;\n"
+      "}\n"
+      "\n"
+      "class MyClass {\n"
+      "  MyClass() {\n"
+      "    (() => foo())();\n"
+      "  }\n"
+      "\n"
+      "  static get field() {\n"
+      "    _bar();\n"
+      "  }\n"
+      "\n"
+      "  static foo() {\n"
+      "    fooHelper() {\n"
+      "      field;\n"
+      "    }\n"
+      "    fooHelper();\n"
+      "  }\n"
+      "}\n"
+      "\n"
+      "main() {\n"
+      "  (() => new MyClass())();\n"
+      "}\n";
+  Dart_Handle lib = TestCase::LoadTestScript(kScriptChars, NULL);
+  EXPECT_VALID(lib);
+  Dart_Handle result = Dart_Invoke(lib, Dart_NewString("main"), 0, NULL);
+  EXPECT_ERROR(
+      result,
+      "Unhandled exception:\n"
+      "MyException\n"
+      "#0      baz (dart:test-lib:2:3)\n"
+      "#1      _OtherClass._OtherClass._named (dart:test-lib:7:8)\n"
+      "#2      globalVar= (dart:test-lib:12:3)\n"
+      "#3      _bar (dart:test-lib:16:3)\n"
+      "#4      MyClass.field (dart:test-lib:25:9)\n"
+      "#5      MyClass.foo.fooHelper (dart:test-lib:30:7)\n"
+      "#6      MyClass.foo (dart:test-lib:32:14)\n"
+      "#7      MyClass.MyClass.<anonymous closure> (dart:test-lib:21:15)\n"
+      "#8      MyClass.MyClass (dart:test-lib:21:18)\n"
+      "#9      main.<anonymous closure> (dart:test-lib:37:10)\n"
+      "#10     main (dart:test-lib:37:24)");
+}
+
 #endif  // defined(TARGET_ARCH_IA32) || defined(TARGET_ARCH_X64).
 
 }  // namespace dart