fix #16482 Regression: _WidgetBase#placeAt() can't be used on a
DocumentFragment

* added tests for placement using document fragment
* updated WidgetBase.placeAt to allow a document fragment
Limit background iframe to IE; it's no longer needed on other browsers.
Also switch test from java applet to PDF, since the java applet wasn't loading correctly.
Fixes #17811, refs #11822.
Avoid double destroy when handle has multiple destroy methods
(ex: destroy() and cancel()).  Fixes #17763.

Thanks Benjamin Santalucia for patch!
avoid more webkit spurious warnings, fixes #17824
Fix TextBox.on("keypress", ...), fixes #17826, refs #17154.
Also adds test case for #17154 (TextBox in Toolbar).
hardcode test locale to en-us to avoid spurious failures, fixes #17818
skip robot tests on iOS and android, refs #17819, #17820
avoid timeout on CheckBoxMixin test, refs #17819, #17820
Convert most remaining AMD test files to use boilerplate.js.
Boilerplate.js sets the locale to en-us, avoiding spurious test
failures on non-US locales.

Refs #17818.
hardcode test locale to en-us to avoid spurious failure, refs #17818
Avoid spurious test failures on iOS, refs #17819, #17820.
Dojo/on gets upset if touchstart events don't define a changedTouches[0] element.