Increase coverage for the Intl.NumberFormat class contructor by adding
tests for checking that it calls ToObject on the locales argument.

[v8-test262-automation] Updated curation log with latest revision sha's from export and changed files.
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[v8-test262-automation] Changes from https://github.com/v8/v8.git at sha 69a502ce on Thu Sep 27 2018 18:35:31 GMT+0000 (Coordinated Universal Time)

[javascriptcore-test262-automation] Updated curation log with latest revision sha's from export and changed files.
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[javascriptcore-test262-automation] Changes from https://github.com/webkit/webkit.git at sha 13bea0a046 on Thu Sep 27 2018 18:30:16 GMT+0000 (Coordinated Universal Time)

Rework the available tests for Intl.NumberFormat.prototype.formatToParts
to improve consistency and readability.

Add an assertion to the test for default parameters in Intl.NumberFormat's
method formatToParts checking that both the values are equal to the correct
result.

[v8-test262-automation] Updated curation log with latest revision sha's from export and changed files.
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[v8-test262-automation] Changes from https://github.com/v8/v8.git at sha a345e766 on Wed Sep 26 2018 18:32:28 GMT+0000 (Coordinated Universal Time)

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Fix #1794

The spec changed in <https://github.com/tc39/proposal-intl-locale/pull/59>.

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[javascriptcore-test262-automation] Changes from https://github.com/webkit/webkit.git at sha 18dbcb73a5 on Mon Sep 24 2018 18:28:03 GMT+0000 (Coordinated Universal Time)

This will allow implementations to test the rest of the number formatting tests,
even if the extra precision support isn't implemented.

Add missing explicit ToString conversion for symbol values and ensure the expected NaN result is a (locale-dependent) string

Import test changes from V8

[v8-test262-automation] Updated curation log with latest revision sha's from export and changed files.
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[v8-test262-automation] Changes from https://github.com/v8/v8.git at sha 1e6d9607 on Tue Sep 25 2018 18:31:03 GMT+0000 (Coordinated Universal Time)

The tests for the parsing of postfix increment, postfix decrement,
prefix increment, and prefix decrement were expressed using `eval`.
This made the tests more complex than necessary and also prevented the
tests from providing value to ECMAScript parsers.

Remove the use of `eval` and instead express the expectations with
literal source text.

Import test changes from V8

Import test changes from JavaScriptCore

[v8-test262-automation] Updated curation log with latest revision sha's from export and changed files.
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[v8-test262-automation] Changes from https://github.com/v8/v8.git at sha 06354392 on Fri Sep 21 2018 18:29:36 GMT+0000 (Coordinated Universal Time)

[javascriptcore-test262-automation] Updated curation log with latest revision sha's from export and changed files.
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[javascriptcore-test262-automation] Changes from https://github.com/webkit/webkit.git at sha d51ed02c2b on Fri Sep 21 2018 18:26:42 GMT+0000 (Coordinated Universal Time)

[v8-test262-automation] Updated curation log with latest revision sha's from export and changed files.
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[v8-test262-automation] Changes from https://github.com/v8/v8.git at sha a9b9c338 on Wed Sep 19 2018 18:27:33 GMT+0000 (Coordinated Universal Time)

[javascriptcore-test262-automation] Updated curation log with latest revision sha's from export and changed files.
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[javascriptcore-test262-automation] Changes from https://github.com/webkit/webkit.git at sha fc056044dc on Wed Sep 19 2018 18:25:12 GMT+0000 (Coordinated Universal Time)