Disable emoji popup in quoted field
### Summary When typing code, colons are used a lot and the emoji popup gets triggered and that is almost never the desired outcome. ### Steps to reproduce 1. Start a code review, make a comment 2. Type ``` triple backticks to start a code block 3. Start writing a python function, type a colon: ![Screenshot_2018-03-30_11-23-27](/uploads/932848fb31f3f62f6afe65f86e0c71df/Screenshot_2018-03-30_11-23-27.png) It also pops-up when making the indentation on the next line: ![Screenshot_2018-03-30_11-29-13](/uploads/f10d5d352412ce03203614799572a25b/Screenshot_2018-03-30_11-29-13.png)
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