New Additions

• Provide goog.labs.userAgent.USE_CLIENT_HINTS_OVERRIDE as a runtime-override mechanism for overriding USE_CLIENT_HINTS in production builds. (41e7935bd56c0df423302a95695eab9f83cad586)
• Add new functions to goog.iter to support rewriting existing ES4 iterators to use ES6 iteration semantics. (a73ad89b281b85e5d3b5436e320af547355f02bf)

Backwards Incompatible Changes

• Remove implementations of goog.iter.Iterator#next within Closure Library. As of this change, it's expected that all users of goog.iter.Iterator are calling the new name for this function, #nextValueOrThrow. (0fc677a62bb4c8dcdf617d0d0d9dac7c68c3158f)
• Deleted goog.dom.pattern package (54209b6f5453f16037658807b13b8088352d1af6)
• The noreferrer option can no longer be set for modern browsers on sites that set a referrer-policy of unsafe-url (f2c85d1699f833bcc781fe13786adac90163bac2)

Other Changes

• Add native ECMAScript support for modern browsers. (16d7b839c422a7d122bcad17cf8935f7d4e134aa)
• Introduces a new configuration object that can be passed to the MockClock constructor. (fd93eae1804ad0f0b69ff94e27fdf942801f7390)
• Make bubble innerHTML assignment Trusted Types compatible. (83aa32c385b6392934eaf30fc7ed82ce51041d92)
• Add support for aria-current to goog.a11y.aria.State. (08f8ee435636acb91621d8a3f01756249b86cd96)
• Fixes error in Safari browser in native ECMAScript mode. (5a49c85b2dd47e3134c795cc1c7897dcafcce2fc)
• Add Intl native support in DateTimeFormat. (ed3f21737413d5929feb6a8a6631177963aa28a1)
• Make deps array of ModuleInfo non-nullable. (1c8d94c7b1148e8e37b2b2e489cb7da663cb21f2)
• Improve EqualToIgnoringWhitespaceMatches to ignore whitespace on both strings. (09d924faa7fdc389fa6de390a0a755b4d63d0dcf)
• Clean up 'var' to 'const' or 'let'. (fcb893ed0b18bbd8b8ac6cb06ba133ef9814906d)