* unpaired surrogate escape sequences

Increase coverage for the Intl.NumberFormat constructor by adding tests
checking if appropriate default values are used.

[v8-test262-automation] Updated curation log with latest revision sha's from export and changed files.
    sourceRevisionAtLastExport: d2e0166d targetRevisionAtLastExport: 67c244b69

[v8-test262-automation] Changes from https://github.com/v8/v8.git at sha d2e0166d on Fri Sep 28 2018 18:33:38 GMT+0000 (Coordinated Universal Time)

[javascriptcore-test262-automation] Updated curation log with latest revision sha's from export and changed files.
    sourceRevisionAtLastExport: f2e2ad6325 targetRevisionAtLastExport: f4f5a415f

[javascriptcore-test262-automation] Changes from https://github.com/webkit/webkit.git at sha f2e2ad6325 on Fri Sep 28 2018 18:30:38 GMT+0000 (Coordinated Universal Time)

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

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.
    sourceRevisionAtLastExport: 69a502ce targetRevisionAtLastExport: 67fc22e98

[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.
    sourceRevisionAtLastExport: 13bea0a046 targetRevisionAtLastExport: d544eace

[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.
    sourceRevisionAtLastExport: a345e766 targetRevisionAtLastExport: d1fe93a7

[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)

[javascriptcore-test262-automation] Updated curation log with latest revision sha's from export and changed files.
    sourceRevisionAtLastExport: 3353b2924e targetRevisionAtLastExport: b0b5c9f9e

Fix #1794

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

[javascriptcore-test262-automation] Updated curation log with latest revision sha's from export and changed files.
    sourceRevisionAtLastExport: 18dbcb73a5 targetRevisionAtLastExport: cd95f95c

[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