Currently function like "() => 239" contains offset 3 as begin of function and 8 as end of function.
This CL changes this to 6 and 9 respectively.

BUG=chromium:566801
R=yangguo@chromium.org,dgozman@chromium.org
TBR=adamk@chromium.org
CQ_INCLUDE_TRYBOTS=master.tryserver.blink:linux_precise_blink_rel

Review-Url: https://codereview.chromium.org/2488493003
Cr-Commit-Position: refs/heads/master@{#40864}