Test new emmet features

[egamma]

Testing #7909

• any platform @Tyriar

Known limitation #8205 (no atomic undo).

Features to test

• Emmet preferences/settings (see Support for Emmet preferences and syntaxProfiles #7926 for a demo)

For documentation and demos of these features pls see description of #8155.

• Expand Abbreviation
• Balance
• Go to Matching Pair
• Wrap with Abbreviation
• Go to Edit Point
• Select Item
• Toggle Comment (@Tyriar: "does not seem to be supported Emmet toggle comment is not supported #8452")
• Split/Join Tag
• Remove Tag
• Merge Lines
• Update Image Size
• Evaluate Math Expression
• Increment/Decrement Number
• Reflect CSS Value
• Encode/Decode Image to data:URL

[mrmlnc]

PR welcome?