DevTools: [Tests] Clear localStorage only when starting /inspector/ or /inspector-enabled/ test

Clearing the devtools' localStorage when showing its window is wrong, since this makes it
impossible to execute subsequent openings of the devtools with retained settings in a single test.

R=pfeldman
BUG=335893

Review URL: https://codereview.chromium.org/130703005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@245991 0039d316-1c4b-4281-b951-d872f2087c98
9 files changed