Issue title: .php files become blank sometimes
 Issue body: Issue Type: <b>Bug</b>

i just notice since two days my some php files goes blank after closing it.

when i reopen its completely blank file.

VS Code version: Code 1.23.1 (d0182c3417d225529c6d5ad24b7572815d0de9ac, 2018-05-10T17:11:17.614Z)
OS version: Windows_NT x64 10.0.17134

<details>
<summary>System Info</summary>

|Item|Value|
|---|---|
|CPUs|Intel(R) Core(TM) i5-3230M CPU @ 2.60GHz (4 x 2594)|
|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>native_gpu_memory_buffers: disabled_software<br>rasterization: disabled_software<br>video_decode: enabled<br>video_encode: enabled<br>vpx_decode: unavailable_software<br>webgl: enabled<br>webgl2: enabled|
|Memory (System)|3.87GB (0.51GB free)|
|Process Argv|C:\Program Files\Microsoft VS Code\Code.exe|
|Screen Reader|no|
|VM|0%|

</details><details><summary>Extensions (13)</summary>

Extension|Author (truncated)|Version
---|---|---
rails|bun|0.5.7
bracket-pair-colorizer|Coe|1.0.55
prettier-vscode|esb|1.3.1
php-debug|fel|1.12.3
php-intellisense|fel|2.3.2
php-pack|fel|1.0.1
auto-close-tag|for|0.5.6
auto-rename-tag|for|0.0.15
vscode-apache|mrm|1.1.1
python|ms-|2018.4.0
indent-rainbow|ode|7.2.2
Ruby|reb|0.18.0
html-css-class-completion|Zig|1.17.1


</details>
<!-- generated by issue reporter -->
 Comments: 
 Comment 0: (Experimental duplicate detection)
Thanks for submitting this issue. Please also check if it is already covered by an existing one, like:
- [Terminal is blank and cannot enter commands (#46078)](https://www.github.com/Microsoft/vscode/issues/46078) <!-- score: 0.507 -->
<!-- potential_duplicates_comment -->
 Comment 1: This issue is caused by an extension, please file it with the repository (or contact) the extension has linked in its overview in VS Code or the [marketplace](https://aka.ms/vscodemarketplace) for VS Code. See also our [issue reporting](https://aka.ms/vscodeissuereporting) guidelines.

Happy Coding!
{'source': 'GithubIssues', 'repo_name_with_owner': 'Microsoft/vscode', 'issue_id': 328442119, 'repo_stars': 77599.0}