[html] don't let '/' trigger a suggest in embedded JavaScript

Issue Type: <b>Bug</b> Create and save a new .html file. Add a script tag, such as: ``` <script> function main() { /**/ } </script> ``` You will notice that after typing the closing slash, IntelliSense pops up (leading to potential unintended insertions if Enter is pressed, for example). If the identical JavaScript code is put into a .js file, the behavior does not occur. VS Code version: Code 1.45.1 (5763d909d5f12fe19f215cbfdd29a91c0fa9208a, 2020-05-14T08:27:35.169Z) OS version: Windows_NT x64 10.0.18363 <details> <summary>System Info</summary> |Item|Value| |---|---| |CPUs|Intel(R) Core(TM) i7-7700HQ CPU @ 2.80GHz (8 x 2808)| |GPU Status|2d_canvas: enabled<br>flash_3d: enabled<br>flash_stage3d: enabled<br>flash_stage3d_baseline: enabled<br>gpu_compositing: enabled<br>multiple_raster_threads: enabled_on<br>oop_rasterization: disabled_off<br>protected_video_decode: enabled<br>rasterization: enabled<br>skia_renderer: disabled_off_ok<br>video_decode: enabled<br>viz_display_compositor: enabled_on<br>viz_hit_test_surface_layer: disabled_off_ok<br>webgl: enabled<br>webgl2: enabled| |Load (avg)|undefined| |Memory (System)|15.86GB (8.52GB free)| |Process Argv|| |Screen Reader|no| |VM|0%| </details><details><summary>Extensions (2)</summary> Extension|Author (truncated)|Version ---|---|--- vscode-eslint|dba|2.1.5 python|ms-|2020.5.78807 </details> <!-- generated by issue reporter -->