Fix running layout tests
Fix running layout tests

In crrev.com/c/2520088 the blink web_tests infrastructure started using
a module that is in Python 3, but not 2. This started crashing our `npm
run test`, since we force the python version. Based on the comments on
the original CL, we should call the Python script directly and then
everything works as expected.

R=8915f5d5c39a08c5a3e8a8d7314756e4580816f9@chromium.org

Change-Id: Iafe123e6adf792da940d3ca605e2eddd49ee5eba
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/2563820
Auto-Submit: Tim van der Lippe <dba8716ee7f8d16236046f74d2167cb94410f6ed@chromium.org>
Reviewed-by: Paul Lewis <8915f5d5c39a08c5a3e8a8d7314756e4580816f9@chromium.org>
Commit-Queue: Tim van der Lippe <dba8716ee7f8d16236046f74d2167cb94410f6ed@chromium.org>

ChromeDevTools/devtools-frontend,ChromeDevTools/devtools-frontend,ChromeDevTools/devtools-frontend,ChromeDevTools/devtools-frontend,ChromeDevTools/devtools-frontend,ChromeDevTools/devtools-frontend