Reported on github whatwg/html as
https://github.com/whatwg/html/issues/2556

Blink side fix + MTL unit test at https://codereview.chromium.org/2839563002/
neis: Would you mind writing a WPT test?

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/f6089442785c7dd2e1fcfa54f53e38e3f7b951f6

commit f6089442785c7dd2e1fcfa54f53e38e3f7b951f6
Author: neis <neis@chromium.org>
Date: Thu Apr 27 14:28:09 2017

[modules] Add simple test concerning instantiation failure.

BUG= chromium:714521 

Review-Url: https://codereview.chromium.org/2839913002
Cr-Commit-Position: refs/heads/master@{#467669}

[add] https://crrev.com/f6089442785c7dd2e1fcfa54f53e38e3f7b951f6/third_party/WebKit/LayoutTests/external/wpt/html/semantics/scripting-1/the-script-element/module/instantiation-error-1.html
[add] https://crrev.com/f6089442785c7dd2e1fcfa54f53e38e3f7b951f6/third_party/WebKit/LayoutTests/external/wpt/html/semantics/scripting-1/the-script-element/module/instantiation-error-1.js

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/321b6ea1a1e2f392c629e2f074ae509a3aaefc42

commit 321b6ea1a1e2f392c629e2f074ae509a3aaefc42
Author: kouhei <kouhei@chromium.org>
Date: Fri Apr 28 03:57:48 2017

[ES6 modules] Return previous error when an instantiation is reattempt.

Before this CL, when instantiation was reattempt for previously errored module,
ModuleTreeLinker::Instantiate() crashed.

This CL updates the code to follow whatwg/html update:
https://github.com/whatwg/html/pull/2559
so that we rethrow previous error when instantiation is reattempt.
TEST=webkit_unit_test --gtest_filter=ModuleTreeLinkerTest.FetchTreePreviousInstantiationFailure
BUG= 594639 , 714521 

Review-Url: https://codereview.chromium.org/2839563002
Cr-Commit-Position: refs/heads/master@{#467882}

[modify] https://crrev.com/321b6ea1a1e2f392c629e2f074ae509a3aaefc42/third_party/WebKit/Source/core/dom/Modulator.h
[modify] https://crrev.com/321b6ea1a1e2f392c629e2f074ae509a3aaefc42/third_party/WebKit/Source/core/dom/ModulatorImpl.cpp
[modify] https://crrev.com/321b6ea1a1e2f392c629e2f074ae509a3aaefc42/third_party/WebKit/Source/core/dom/ModulatorImpl.h
[modify] https://crrev.com/321b6ea1a1e2f392c629e2f074ae509a3aaefc42/third_party/WebKit/Source/core/dom/ModuleScript.h
[modify] https://crrev.com/321b6ea1a1e2f392c629e2f074ae509a3aaefc42/third_party/WebKit/Source/core/loader/modulescript/ModuleTreeLinker.cpp
[modify] https://crrev.com/321b6ea1a1e2f392c629e2f074ae509a3aaefc42/third_party/WebKit/Source/core/loader/modulescript/ModuleTreeLinkerTest.cpp
[modify] https://crrev.com/321b6ea1a1e2f392c629e2f074ae509a3aaefc42/third_party/WebKit/Source/core/testing/DummyModulator.cpp
[modify] https://crrev.com/321b6ea1a1e2f392c629e2f074ae509a3aaefc42/third_party/WebKit/Source/core/testing/DummyModulator.h