Add TypeScript declarations to iron-demo-helpers. (#71)

* Generate minimal package.json from bower.json
* Update and/or configure type declarations.

.gitignore

@@ -1,2 +1,3 @@
 bower_components*
 bower-*.json
+node_modules

.travis.yml

@@ -3,6 +3,10 @@ sudo: required
 before_script:
   - npm install -g polymer-cli
   - polymer install --variants
+  - >-
+    npm run update-types && git diff --exit-code || (echo -e
+    '\n\033[31mERROR:\033[0m Typings are stale. Please run "npm run
+    update-types".' && false)
 node_js: stable
 addons:
   firefox: latest

demo-pages-shared-styles.d.ts

@@ -0,0 +1,14 @@
+/**
+ * DO NOT EDIT
+ *
+ * This file was automatically generated by
+ *   https://github.com/Polymer/gen-typescript-declarations
+ *
+ * To modify these typings, edit the source file(s):
+ *   demo-pages-shared-styles.html
+ */
+
+/// <reference path="../polymer/types/polymer.d.ts" />
+/// <reference path="../iron-flex-layout/iron-flex-layout.d.ts" />
+/// <reference path="../font-roboto/roboto.d.ts" />
+

demo-snippet.d.ts

@@ -0,0 +1,59 @@
+/**
+ * DO NOT EDIT
+ *
+ * This file was automatically generated by
+ *   https://github.com/Polymer/gen-typescript-declarations
+ *
+ * To modify these typings, edit the source file(s):
+ *   demo-snippet.html
+ */
+
+/// <reference path="../polymer/types/polymer.d.ts" />
+/// <reference path="../marked-element/marked-element.d.ts" />
+/// <reference path="../prism-element/prism-highlighter.d.ts" />
+/// <reference path="../prism-element/prism-theme-default.d.ts" />
+
+/**
+ * `demo-snippet` is a helper element that displays the source of a code snippet and
+ * its rendered demo. It can be used for both native elements and
+ * Polymer elements.
+ *
+ *     Example of a native element demo
+ *
+ *         <demo-snippet>
+ *           <template>
+ *             <input type="date">
+ *           </template>
+ *         </demo-snippet>
+ *
+ *     Example of a Polymer <paper-checkbox> demo
+ *
+ *         <demo-snippet>
+ *           <template>
+ *             <paper-checkbox>Checkbox</paper-checkbox>
+ *             <paper-checkbox checked>Checkbox</paper-checkbox>
+ *           </template>
+ *         </demo-snippet>
+ *
+ * ### Styling
+ *
+ * The following custom properties and mixins are available for styling:
+ *
+ * Custom property | Description | Default
+ * ----------------|-------------|----------
+ * `--demo-snippet` | Mixin applied to the entire element | `{}`
+ * `--demo-snippet-demo` | Mixin applied to just the demo section | `{}`
+ * `--demo-snippet-code` | Mixin applied to just the code section | `{}`
+ */
+interface DemoSnippetElement extends Polymer.Element {
+  _markdown: string|null|undefined;
+  attached(): void;
+  detached(): void;
+  _updateMarkdown(): void;
+  _copyToClipboard(): any;
+  _resetCopyButtonState(): void;
+}
+
+interface HTMLElementTagNameMap {
+  "demo-snippet": DemoSnippetElement;
+}