Jumbo for blink/core generated files as well (saving 8 CPU minutes)

The target that compiles generated files does not use the same
template as other code in blink core so it didn't automatically become
jumbo enabled. Since it's a non-negliable part of the build time (~1%)
this patch enables jumbo for this target as well.

R=fs@opera.com
BUG=713137

Review-Url: https://codereview.chromium.org/2973603003
Cr-Commit-Position: refs/heads/master@{#485267}
2 files changed