[vscode] css code completion doesn't work - Cannot read property 'Deprecated' of undefined

[shahar-h]

Bug Description:

There are no completion results when working on css file.

Steps to Reproduce:

1. Create an empty css file.
2. Hit ctrl + space.

There are no results:

In addition the following error appears in browser console:

TypeError: Cannot read property 'Deprecated' of undefined
    at y (c:\SAPDevelop\repos\theia\plugins\vscode-builtin-css-language-features\extension\client\dist\cssMain.js:1:163850)
    at c:\SAPDevelop\repos\theia\plugins\vscode-builtin-css-language-features\extension\client\dist\cssMain.js:1:163962
    at C (c:\SAPDevelop\repos\theia\plugins\vscode-builtin-css-language-features\extension\client\dist\cssMain.js:1:163998)
    at Array.map (<anonymous>)
    at asCompletionResult (c:\SAPDevelop\repos\theia\plugins\vscode-builtin-css-language-features\extension\client\dist\cssMain.js:1:170409)
    at http://localhost:3000/vs/editor/editor.main.js:1607:31

vscode:

Additional Information

• Operating System: Windows 10
• Theia Version: master

[zouyi100]

I think the file with preprocessor style language like scss, less has the same problem.