[ES6 modules] update run-a-module-script algorithm and fix import() error crash

This CL updates ModuleImplBase::ExecuteModule to match the latest spec text.
The change also fix crash when dynamic import() is attempt on module tree w/ instantiation error.

Test: external/wpt/html/semantics/scripting-1/the-script-element/module/dynamic-import/dynamic-imports-error.html
Bug: 763597
Change-Id: Icae37257492d3b2a0885fd571ac745f9de49cc6e
Reviewed-on: https://chromium-review.googlesource.com/711634
Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Commit-Queue: Kouhei Ueno <kouhei@chromium.org>
Cr-Commit-Position: refs/heads/master@{#507916}
3 files changed