New Additions

• Define ES6 Iterator #next on goog.iter.Iterator, in preparation for implementing it on all subclasses. (d5fc48c78592b4327ba052f4a935a9312788725b)
• Add goog.labs.userAgent.testUtil. (d860c5ac5ac25a01eb5a1a5c8b29862d7f5361a9)
• Add APIs to get userAgentData-aware browser and platform versions. For the browser, the version can now be retrieved for a specific brand. For both browser and platform, the full version is supplied as a "high-entropy" object. (246750e0d1973b88535cc37dae7d7c7cd0b2e981)
• Closure Library goog.iter.Iterator instances implement the ES6 iteration protocol alongside the existing ES4 implementation (available via the #nextValueOrThrow function). Iterators still call (and transform) the ES4 iterator function in child iterators, and this will be changed in future versions of Closure Library (to call the ES6 interface). (cd81947ae69a43f996ee87009850eb795e4badc0)
• Add browser.loadFullVersions. Additionally, remove an assumption that fullVersionList will be available in a particular future version of Chrome. (57beea47d30d7123dc2268972f20b544e501432b)
• Improve the types for goog.iter.reduce so that the accumulator can be a different type than values in the iterator. (55b2883a7a558d0a1bea61a1f084aba69d80825a)

Backwards Incompatible Changes

• goog.dom.TextRangeIterator#skipTag no longer directly throws goog.iter.StopIteration. Instead, if it has skipped to (or over) the end of the range, iteration end will be signaled on the next call to #nextValueOrThrow. (06dc75fc00e89b69ec898fd21da31f6b430c97b5)
• Make ModuleManager filter "synthetic" modules to ensure the list of loading module ids is accurate. (f74bfb1bbe65611c8c222c193de973d3e72a5c4c)
• Re-map the goog.define goog.events.USE_LAYER_XY_AS_OFFSET_XY to goog.events.BrowserEvent.USE_LAYER_XY_AS_OFFSET_XY. (28701030e95f3aa68cc7cd59fc6cacb55b9fd67b)
• Use a stable-sort when sorting css rules by specificity (5411d9637649ed087ba72f6ecd5b4171f215b15f)

Other Changes

• goog.string.padNumber now handles negative numbers. (acc79f7a62501b5491aa3457ccd4f0d6989e62e1)
• Add HTMLElement helper methods to dom.js. (7a9f0001ba6119db4fa682ef0ad80076df54d021)
• Implemented the support for the new WebChannel option: encodeInitMessageHeaders. (cfb2e44c314fa5d2c048b0e8b2299aac6092ed5b)
• Add '#' to SafeStyle list of allowed characters inside functions. (0726fdeb8b7bf884c4184cec00a4bf11302ece11)
• Added configure function to activeModuleManager (a63fcec700ad0be2b22e9282e3e93f42f243ec48)
• Do not assume userAgentData brand names for browsers that don't support it yet. (6a9094de3bea29ee8fbba50cd044bbdfdd19fcec)
• Do not check userAgentData.brands to determine whether the current browser is Amazon Silk. (c8961ac3395ddc906d52adb4ea21f5b102c830fc)
• Move the check that determines loader support for extra edges to the point at which the manager delegates to the module loader. (c70f4b7c51737e65e0418d47a242d5da77fee8c6)
• add a custom pluggable equality interface for findDifferences and assertObjectEquals. (99d095514a6112011aba0ce32750ba90ac5e05a3)* Add '/' to SafeStyle list of allowed value characters. (2f2707730794daf64bb05b182d2413131e534517)
• Add capital letters to SafeStyle list of allowed characters in functions. (e762b3beaef5ff5db104c711e2f416d3381225df)
• Fix an issue with repeated VoiceOver messages. (0fd0574a17e956fbb1844388be886b28f79393b0)
• Add opt_preserveSpacesAndTabs param to linkifyPlainTextAsHtml. (e9046487595e1c9542cb6f8781b621cd22060d91)
• IE9 and previous are no longer supported with goog.require code loading. (ff4763f19033ecc321379ee96c1530fe05d3ae7e)
• Update with CLDR 40 data. (2a21f12531e1639aa97f2f1415f353cf39419dbb)
• Dates now implement ISO8601 more accurately for very large or negative years. (2dd8283d41f5d759fb079c671ce5582add658037)
• Support Amazon Silk in versionOf, and fix Silk support for newer browsers. (91f1ccfa6b724e085407d7d8f86ad9af82cdd064)
• Delete 'goog.i18n.DateTimeParse.prototype.strictParse'. (21c7f0503670e8b54c4bced7b34cd23c45a42ad2)
• added check for synthetic module before setting module constructor (c152058a28093272e4fa0aa498570e5950750e77)
• Use navigator.userAgentData to identify platforms in goog.labs.userAgent. (b729e7f79652fc7fc37408f955856d2dec37d6f6)
• Don't assume that the presence of userAgentData indicates that the browser is definitely not Firefox or Safari. Also, respect ASSUME_USER_AGENT_DATA in all browser brand checks. (9b0ee8d8c9212db4885bc0ce627a77971542ba21)
• Update with ICU70 / CLDR40 data (b5188f095a75338eeb09ab899fc94946632f453c)