Customizer doesn't load in IE8

[ocean90]

Error message:

Webpage error details

User Agent: Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.1; WOW64; Trident/4.0; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; Media Center PC 6.0)
Timestamp: Mon, 9 May 2016 20:28:34 UTC

Message: Expected identifier
Line: 1454
Char: 7
Code: 0
URI: http://develop.wp.dev/wp-includes/js/underscore.js?ver=1.8.3

[ocean90]

Previously: #30781

[westonruter]

We need to get the QUnit tests running on BrowserStack so that these IE8 issues can be caught automatically.

[adamsilverstein]

Digging into this, so far I have discovered this is theme related. Activating an older theme the customizer loads without error in ie8.

[adamsilverstein]

In 36793.diff​:

• Remove use of reserved word default in Underscore template which breaks IE8.

This code was introduced in r30712 and is inclass-wp-customize-media-control.php - not sure why this cropped up in 4.5 specifically, perhaps something in the customizer load sequence is now using the media control (site logo?) that wasn't previously being used.

This change fixes the issue. Screenshot showing no errors in customizer in IE8:

[westonruter]

In 37417:

Customize: Remove use of reserved word default in Underscore template which breaks IE8.

Fixes regression introduced in r30712.

Props adamsilverstein.
Fixes #36793.

[westonruter]

Re-opening for consideration for 4.5.3

[ocean90]

@adamsilverstein [36769] was the breaking change for 4.5.

[adamsilverstein]

@ocean90 aha that makes more sense. I was using Svn blame, how did you find the breaking change?

[ocean90]

Replying to adamsilverstein:
SVN blame :-)

Go to https://core.trac.wordpress.org/browser/trunk/src/wp-includes/customize/class-wp-customize-media-control.php?annotate=blame&rev=37152&marks=217#L217 and click on the changeset number in the first column.

[ocean90]

In 37450:

Customize: Remove use of reserved word default in Underscore template which breaks IE8.

Fixes regression introduced in [36769].

Merge of [37417] to the 4.5 branch.

Props adamsilverstein.
Fixes #36793.