Do not do compile steps for Coverage

Coverage needs to do compilation in its test step. The primary reason is: the path to the out directory is compiled into the binary, which is why the compile and test steps need to be combined.

BUG=skia:5159
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1889183002
NOTREECHECKS=true

Review URL: https://codereview.chromium.org/1889183002
1 file changed