[folding] folding indicators missing for folded code

Issue Type: <b>Bug</b> For some time the visual studio code has been blocked, it does not display the fragments of code. Suppose I have a code fragment inside an if, when it is blocked accessing this code inside the if is impossible, it is necessary to close the visual code and re-enter sometimes it happens up to 10 times in the day  access the points marked with the red arrow when it is blocked you can not In this image you can see how the code can not be accessed  VS Code version: Code 1.35.1 (c7d83e57cd18f18026a8162d042843bda1bcf21f, 2019-06-12T14:30:02.622Z) OS version: Windows_NT x64 10.0.17134 <details><summary>Extensions (18)</summary> Extension|Author (truncated)|Version ---|---|--- html-snippets|abu|0.2.1 bracket-pair-colorizer|Coe|1.0.61 angular2-snippets|dan|1.0.21 githistory|don|0.4.6 vscode-html-css|ecm|0.2.0 tslint|eg2|1.0.43 auto-close-tag|for|0.5.6 auto-rename-tag|for|0.1.0 Angular2|joh|8.1.1 vscode-extension-auto-import|mop|1.3.3 vscode-language-pack-es|MS-|1.35.1 atom-keybindings|ms-|3.0.6 csharp|ms-|1.20.0 powershell|ms-|2019.5.0 al-formatter|ras|3.0.0 vscode-icons|vsc|8.7.0 JavaScriptSnippets|xab|1.7.2 tslint-snippets|zuo|1.1.0 </details> <!-- generated by issue reporter -->