Prevent keypresses from triggering onNormalizedDisplayChange

This avoids toolbar buttons from becoming disabled in IE11 when
the editor frame is unfocused by keyboard navigation to the
toolbar. The onNormalizedDisplayChange will occur once the entire
editor is blurred.

The ultimate solution is probably to stop using
queryCommandEnabled (like all other RTEs) but that would require
a significant amount of additional effort for diminishing gain.

Fixes #17595.
Remove separate opacity rule for disabled MenuItem icon.

The icon specific rule was presumably created because apps can specify separate enabled
and disabled icons.  Sometimes a disabled icon would be bleached out or black-and-white,
rather than color, and wouldn't need any CSS help to look "disabled".
Thus the icon opacity was set to 1 whereas the text was opacity:0.5.

However, we do need the icon cell to have the the same opacity:0.5 setting for the
purpose of the hovered blue background and hovered border.

Fixes #17031.
Don't call preventDefault() on MSPointerDown/pointerdown event.
Likewise for MSPointerUp/pointerup.
It prevents the mousedown / mouseup events from being emitted.

Fixes #17709.
Increase the timeout of `_justMouseDowned` handler to 13 ms.

Fixes #17668
Fix dropdown positioning problems on mobile when dir=rtl.
Rolls back changes to place.js from 33dc9b874f74e1bf180f9cb6f3c14d13a0fb7a90
about setting drop down's style.right, and instead always sets style.left.

Fixes #17732, refs #5777.
Don't call scrollIntoView() on mouse/touch operations.

Besides being unnecessary, it causes a screen jump when selecting a choice from
a ComboBox drop down menu on an RTL page w/a horizontal scrollbar on iOS.

Fixes #17739.
Add support for labelType in dijit/form/Select, fixes #17746
Removed a space that snuck in there, refs #17746
Fix IE problem with caret disappearing or not moving on ENTER.
Happens with EnterKeyHandling plugin when blockNodeForEnter=BR (the default setting
for an editor without any plugins explicitly specified).

Also fixes FF problem on ENTER with caret moving to beginning of current line,
rather than beginning of next line.

Code changes:

- this.editor.selection.collapse(true) doesn't work well when the selection is the \n at the end of a document.
  So trim() whitespace from the end of the document on load.
- Don't call remove() on the current selection as it causes havoc with the caret.
  Code to call remove() was added in 08c381738d5c1da53099db51848d94fde3c3249d for #12008,
  to remove the &nbsp added, but now I'm handling this in _stripTrailingEmptyNodes()

Unfortunately this change needs to be manually tested,
since doh/robot doesn't know where the caret appears visually.

Fixes #17745, refs #12008.
Add isLoaded check to RichText#getValue to avoid errors when the iframe has not yet loaded.
Fixes #15134.
Fix alignment of right aligned dropdowns, fixes #17744
fixes #16939 IE hangs when switching between multiple editors / refocusing browser window, the problem also happened on IE8 and IE11.
Remove evt.preventDefault() calls on dropdown mouse events.

The evt.preventDefault() on mousedown breaks ComboBox on iOS, by cancelling the mouseup
and click events, thus preventing selection of an option.

According to the comment, the evt.preventDefault() call on mousedown was to
"prevent focus shift on list scrollbar press".
But I still lost focus when clicking the scrollbar, at least on IE8.
Plus which, even if clicking the scrollbar loses focus, it doesn't seem like a problem.

There were also evt.preventDefault() calls on the other events (mouseup, mouseover, etc.) but I
don't see any reason for them.

Fixes #17752 on trunk.
InlineEditBox: destroy save/cancel button widgets, fixes #17748
test for BackgroundIframe on all browsers, refs #16268
Don't treat SPACE as the start of a keyboard search.
Add KeyNavContainer robot test.
Fixes #17766.
Fix menu positioning when opened via keyboard.  Fixes #17769.

Changes include:
  - make keydown handler process context-menu key in addition to shift-F10
  - (for keyboard) open menu around focused node rather than node matching
    this.targetNodeIds / this.selector
  - different approach to avoid repeat contextmenu key event;
    1ms delay in _scheduleOpen() was too short; there's about 100ms between
    the keydown and contextmenu events on IE8
remove unneeded CSS that flummoxes IE, fixes #17672
fix tooltips on SVG nodes on FF, fixes #16310
fixes #17751 use native placeholder support for form inputs