[devtools] Avoid exception when opening with --disable-local-storage
[devtools] Avoid exception when opening with --disable-local-storage

BUG=305729

Review URL: https://codereview.chromium.org/26279010

git-svn-id: bf5cd6ccde378db821296732a091cfbcf5285fbd@159341 bbb929c8-8fbe-4397-9dbb-9b2b20218538

primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs