Select all inside webview inputs is not working

[arjunattam]

Issue Type: Bug

The keyboard action cmd+A does not trigger text selection inside an input field of a webview. From my debugging, the keyboard event gets intercepted by vscode, and is never received by the webview. These closed issues seem to be related:

• Keyboard shortcut for "Select All" doesn't work in certain input text fields #50735
• Fix 38384 selectAll Command for Webviews (previewHTML) #38387

This is affecting my extension (Slack Chat: arjunattam/vscode-chat#22) and I would be happy to send in a PR once the team can confirm it is required.

VS Code version: Code 1.24.1 (24f6262, 2018-06-13T17:41:50.128Z)
OS version: Darwin x64 17.5.0

System Info

Item	Value
CPUs	Intel(R) Core(TM) i5-7360U CPU @ 2.30GHz (4 x 2300)
GPU Status	2d_canvas: enabled flash_3d: enabled flash_stage3d: enabled flash_stage3d_baseline: enabled gpu_compositing: enabled multiple_raster_threads: enabled_on native_gpu_memory_buffers: enabled rasterization: enabled video_decode: enabled video_encode: enabled vpx_decode: enabled webgl: enabled webgl2: enabled
Load (avg)	7, 4, 4
Memory (System)	8.00GB (0.03GB free)
Process Argv	/Applications/Visual Studio Code.app/Contents/MacOS/Electron
Screen Reader	no
VM	0%

Extensions (6)

Extension	Author (truncated)	Version
githistory	don	0.4.1
prettier-vscode	esb	1.5.0
chat	kar	0.3.2
python	ms-	2018.6.0
vsliveshare	ms-	0.3.335
java	red	0.27.0

(1 theme extensions excluded)

[mjbvz]

Duplicate of #8794