Hi everybody,

Just sending out an email blast for visibility regarding https://bugs.webkit.org/show_bug.cgi?id=209694.

This patch:

• Upgrades the Mac ICU headers under Source/WTF/icu from ICU 55 to ICU 62, matching Mojave
• Introduces a minimum ICU version of 60.2 throughout the codebase, as required by GTK for Ubuntu 18.04 LTS

As written in the ChangeLog, the immediate motivations are:

1. To properly establish a minimum ICU version for WebKit as a whole
   (responding to a pain point identified in https://bugs.webkit.org/show_bug.cgi?id=209579)
2. To support the development of ECMA-402 Intl API features, which JSC is quite behind on
   (and which often boil down to exposing ICU functionality to JavaScript)

The only remaining concern of which I am aware is that AppleWin’s ICU headers, stored in WebKitAuxiliaryLibrary.zip, need to be upgraded from ICU 49 to 62 (to match the lib files stored in WebKitSupportLibrary.zip). We do have a potential workaround for this (i.e. having CMake copy the Mac headers to WebKitLibraries/win) but it is feared that this may break Apple-internal builds and we would certainly like to avoid a revert if possible. Any help on this front would be greatly appreciated.

Thanks,

Ross