SCM input box line length warning can get detached on scroll

[mjbvz]

Issue Type: Bug

repro

1. In the scm view
2. Have enough changes the the changes section can be scrolled
3. Enter a long line in the scm input so that the line length warning shows up
4. With the warning visible, scroll the commit list

Bug

The line length warning become detached from the input box:

VS Code version: Code - Insiders 1.47.0-insider (04545fa, 2020-07-02T05:41:12.081Z)
OS version: Darwin x64 19.5.0

System Info

Item	Value
CPUs	Intel(R) Core(TM) i9-9980HK CPU @ 2.40GHz (16 x 2400)
GPU Status	2d_canvas: enabled flash_3d: enabled flash_stage3d: enabled flash_stage3d_baseline: enabled gpu_compositing: enabled metal: disabled_off multiple_raster_threads: enabled_on oop_rasterization: disabled_off protected_video_decode: unavailable_off rasterization: enabled skia_renderer: disabled_off_ok video_decode: enabled viz_display_compositor: enabled_on viz_hit_test_surface_layer: disabled_off_ok webgl: enabled webgl2: enabled
Load (avg)	2, 2, 2
Memory (System)	32.00GB (1.68GB free)
Process Argv	-psn_0_13069430
Screen Reader	no
VM	14%

[joaomoreno]

Decided to hide the validation when the view scrolls, for now.