Improve *What's new in DevTools (Chrome 79)* article (#8235)
Improve *What's new in DevTools (Chrome 79)* article (#8235)

- Clarify which search box got added
- Clarify that coverage only displays if it is available
myakura/WebFundamentals,myakura/WebFundamentals,google/WebFundamentals,google/WebFundamentals,myakura/WebFundamentals,google/WebFundamentals,google/WebFundamentals,myakura/WebFundamentals