Revert of Make sure multi chracter codepoints are deleted correctly (patchset #6...

Revert of Make sure multi chracter codepoints are deleted correctly (patchset #6 id:100001 of https://codereview.chromium.org/1165793007/)

Reason for revert:
Failing Android Tests (dbg) builder: http://build.chromium.org/p/chromium.linux/builders/Android%20Tests%20%28dbg%29/builds/28499

The newly added test seems to be flaky.

Original issue's description:
> Make sure multi chracter codepoints are deleted correctly
>
> deleteSurroundingText() only deletes one character even for multi-character
> codepoint.
>
> On the blink side, we have InputMethodController::extendSelectionAndDelete()
> to make sure selection and deletion respect Unicode boundaries. However,
> AdapterInputConnection keeps track of selection region separately, and this
> value is incorrectly updated.
>
> On top of adding a new test for this case, it extends
> waitAndVerifyEditorCallback to also check the outbound calls to
> InputMethodManager.
>
> The above extension found that testEnterKeyEventWhileComposingText fails
> because there is hidden discrepancy between blink implementation and
> what we report to InputMethodManager. So I've added a TODO for that.
>
> BUG=497091
>
> Committed: https://crrev.com/5f6e036312bc4a978768f5b5971eee1a5ec9f272
> Cr-Commit-Position: refs/heads/master@{#333704}

TBR=aelias@chromium.org,aurimas@chromium.org,bcwhite@chromium.org,tedchoc@chromium.org,changwan@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=497091

Review URL: https://codereview.chromium.org/1173083004

Cr-Commit-Position: refs/heads/master@{#333765}