fix(page): use secondary DOMWorld to drive page.select() (#3809)

This patch starts creating secondary DOMWorld for every connected
page and switches `page.select()` to run inside the secondary world.

Fix #3327.

lib/DOMWorld.js

@@ -44,6 +44,13 @@ class DOMWorld {
     this._detached = false;
   }
 
+  /**
+   * @return {!Puppeteer.Frame}
+   */
+  frame() {
+    return this._frame;
+  }
+
   /**
    * @param {?Puppeteer.ExecutionContext} context
    */
@@ -419,28 +426,6 @@ class DOMWorld {
     await handle.dispose();
   }
 
-  /**
-   * @param {(string|number|Function)} selectorOrFunctionOrTimeout
-   * @param {!Object=} options
-   * @param {!Array<*>} args
-   * @return {!Promise<!Puppeteer.JSHandle>}
-   */
-  waitFor(selectorOrFunctionOrTimeout, options = {}, ...args) {
-    const xPathPattern = '//';
-
-    if (helper.isString(selectorOrFunctionOrTimeout)) {
-      const string = /** @type {string} */ (selectorOrFunctionOrTimeout);
-      if (string.startsWith(xPathPattern))
-        return this.waitForXPath(string, options);
-      return this.waitForSelector(string, options);
-    }
-    if (helper.isNumber(selectorOrFunctionOrTimeout))
-      return new Promise(fulfill => setTimeout(fulfill, /** @type {number} */ (selectorOrFunctionOrTimeout)));
-    if (typeof selectorOrFunctionOrTimeout === 'function')
-      return this.waitForFunction(selectorOrFunctionOrTimeout, options, ...args);
-    return Promise.reject(new Error('Unsupported target type: ' + (typeof selectorOrFunctionOrTimeout)));
-  }
-
   /**
    * @param {string} selector
    * @param {!{visible?: boolean, hidden?: boolean, timeout?: number}=} options