fix cotextmenu cropped

[YueyingLu]

Issue #4681, if available:

Description of changes:
Problem to solve: ContextMenu gets cropped on small mobile screen sizes or with larger the font size. In addition, buttons needs more distance to distinguish separate ones. In the screenshot, it is hard to tell that "Select All" is one button and "Paste" is the next button. Screenshot can be reproduced on demo page with font size 24.

Solution: Buttons display block.
Check if menu gets cropped at bottom. If so opens the menu up(by moving the menu up). When close menu by clicking the "more" button, move menu icon back to the cursor position.

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[codecov]

Codecov Report

Merging #4682 (7cc0c2a) into master (6bf0d68) will increase coverage by 0.00%.
The diff coverage is 37.50%.

@@           Coverage Diff           @@
##           master    #4682   +/-   ##
=======================================
  Coverage   71.17%   71.18%           
=======================================
  Files         553      553           
  Lines       55572    55593   +21     
  Branches    10398    10394    -4     
=======================================
+ Hits        39555    39575   +20     
- Misses      16017    16018    +1     

Flag	Coverage Δ
unittests	71.18% <37.50%> (+<0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
lib/ace/mouse/touch_handler.js	87.86% <37.50%> (-1.75%)	⬇️
lib/ace/editor.js	79.71% <0.00%> (-1.91%)	⬇️
lib/ace/mode/php_laravel_blade_highlight_rules.js	100.00% <0.00%> (ø)
lib/ace/virtual_renderer.js	80.00% <0.00%> (+0.11%)	⬆️
lib/ace/edit_session/folding.js	75.37% <0.00%> (+0.93%)	⬆️
lib/ace/mouse/mouse_handler_test.js	99.51% <0.00%> (+1.15%)	⬆️
lib/ace/lib/event.js	72.94% <0.00%> (+9.35%)	⬆️

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