v8binding: Fix ToFloat to throw

Adds a missing check of exception_state.HadException().

Comment about crbug.com/939598 is not correct because of
    unrestricted float (Web IDL) => ToFloat (Blink)
    float (Web IDL) => ToRestrictedFloat (Blink)
In case of 'unrestricted float', it shouldn't throw an
exception.

Bug: 939598
Change-Id: Ibda1cb445b630f38a8e3ab52c6839a49020d6941
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1574997
Reviewed-by: Hitoshi Yoshida <peria@chromium.org>
Commit-Queue: Yuki Shiino <yukishiino@chromium.org>
Cr-Commit-Position: refs/heads/master@{#652538}
1 file changed