[Extern Generation] Normify extern enum property names

tools/json_schema_compiler/js_externs_generator_test.py

Index: tools/json_schema_compiler/js_externs_generator_test.py
diff --git a/tools/json_schema_compiler/js_externs_generator_test.py b/tools/json_schema_compiler/js_externs_generator_test.py
index b74260daf86e5fcc0932bdd79b6501d651356fe6..1c9f6478d136408710cbfff49678c16cd7b174ec 100755
--- a/tools/json_schema_compiler/js_externs_generator_test.py
+++ b/tools/json_schema_compiler/js_externs_generator_test.py
@@ -163,6 +163,12 @@ fake_json = """// Copyright 2014 The Chromium Authors. All rights reserved.
   {
     "namespace": "fakeJson",
     "description": "Fake JSON API Stuff",
+    "types": [ {
+      "id": "CrazyEnum",
+      "type": "string",
+      "enum": ["camelCaseEnum", "Non-Characters", "5NumFirst", \
+"3Just-plainOld_MEAN"]
+    } ],
     "functions": [ {
       "name": "funcWithInlineObj",
       "type": "function",
@@ -231,6 +237,17 @@ json_expected = """// Copyright %s The Chromium Authors. All rights reserved.
 chrome.fakeJson = {};
 
 /**
+ * @enum {string}
+ * @see https://developer.chrome.com/extensions/fakeJson#type-CrazyEnum
+ */
+chrome.fakeJson.CrazyEnum = {
+  CAMEL_CASE_ENUM: 'camelCaseEnum',
+  NON_CHARACTERS: 'Non-Characters',
+  _5NUM_FIRST: '5NumFirst',
+  _3JUST_PLAIN_OLD_MEAN: '3Just-plainOld_MEAN',
+};
+
+/**
  * @param {{
  *   foo: (boolean|undefined),
  *   bar: number,