[JSC] Specifying same module entry point multiple times cause TypeError

[JSC] Specifying same module entry point multiple times cause TypeError
https://bugs.webkit.org/show_bug.cgi?id=164858

Reviewed by Saam Barati.

Source/JavaScriptCore:

Allow importing the same module multiple times. Previously, when specifying the same
module in the <script type="module" src="here">, it throws TypeError.

* builtins/ModuleLoaderPrototype.js:
(requestFetch):
(requestTranslate):
(requestInstantiate):
(requestSatisfy):

LayoutTests:

* js/dom/modules/module-load-same-module-from-different-entry-point-in-src-expected.txt: Added.
* js/dom/modules/module-load-same-module-from-different-entry-point-in-src.html: Added.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@209172 268f45cc-cd09-0410-ab3c-d52691b4dbfc