You can temporarily change gn args to disable compilation.

I think.. personally, I'd rather treat my js compilation similar to a C++
compile error though - it's a good way to catch simple mistakes :)

Still, there's probably a neat way to make a separate chain of targets in
the js_unit_test template that skips the type checking step.

I think https://chromium-review.googlesource.com/c/chromium/src/+/1198665 is what you're after?

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/947b83bebbe79b610e2144d312b1bc12a71448e5

commit 947b83bebbe79b610e2144d312b1bc12a71448e5
Author: Trent Apted <tapted@chromium.org>
Date: Tue Sep 04 04:12:18 2018

Gallery: Split out closure type-checking from unittest html generation.

Currently `js_unit_tests("foo")` declares a single target with
both closure type-checking and unittest html generation as dependencies.

This CL has it generate two targets instead. One for html generation
(foo), and another for typechecking (foo_type_check).

Bug:  879066 
Change-Id: Ic8b411d89d2dd6ec91c40e102d42288c66fc8157
Reviewed-on: https://chromium-review.googlesource.com/1198665
Reviewed-by: Luciano Pacheco <lucmult@chromium.org>
Commit-Queue: Trent Apted <tapted@chromium.org>
Cr-Commit-Position: refs/heads/master@{#588450}
[modify] https://crrev.com/947b83bebbe79b610e2144d312b1bc12a71448e5/ui/file_manager/gallery/js/BUILD.gn
[modify] https://crrev.com/947b83bebbe79b610e2144d312b1bc12a71448e5/ui/file_manager/gallery/js/image_editor/BUILD.gn
[modify] https://crrev.com/947b83bebbe79b610e2144d312b1bc12a71448e5/ui/file_manager/js_unit_tests.gni