assets: Add Noto Color Emoji back again, for use on Android

Downloaded from:
  https://github.com/googlefonts/noto-emoji/tree/d79d23e68/fonts

We removed this in a1da95a, but we want to add it back now that
we're more confident that it will work on Android. In the time since
a1da95a, we learned that COLRv1 fonts just never work on
iOS/macOS; they aren't supported:
  flutter/flutter#134897 (comment)

So, when trying to explain why this font wasn't working in a test on
my iPhone, it seems less necessary to consider a possible unknown
factor that might affect some Android installs too. It was likely
explained just by the fact that the format doesn't have iOS support.

This fixes zulip#435, where the "Licenses" page was broken because we
forgot to remove its reference to the Noto Color Emoji license that
we removed in a1da95a.

Fixes: zulip#404
Fixes: zulip#435

Author: chrisbobbe

assets/Noto_Color_Emoji/LICENSE

@@ -0,0 +1,92 @@
+This Font Software is licensed under the SIL Open Font License,
+Version 1.1.
+
+This license is copied below, and is also available with a FAQ at:
+http://scripts.sil.org/OFL
+
+-----------------------------------------------------------
+SIL OPEN FONT LICENSE Version 1.1 - 26 February 2007
+-----------------------------------------------------------
+
+PREAMBLE
+The goals of the Open Font License (OFL) are to stimulate worldwide
+development of collaborative font projects, to support the font
+creation efforts of academic and linguistic communities, and to
+provide a free and open framework in which fonts may be shared and
+improved in partnership with others.
+
+The OFL allows the licensed fonts to be used, studied, modified and
+redistributed freely as long as they are not sold by themselves. The
+fonts, including any derivative works, can be bundled, embedded,
+redistributed and/or sold with any software provided that any reserved
+names are not used by derivative works. The fonts and derivatives,
+however, cannot be released under any other type of license. The
+requirement for fonts to remain under this license does not apply to
+any document created using the fonts or their derivatives.
+
+DEFINITIONS
+"Font Software" refers to the set of files released by the Copyright
+Holder(s) under this license and clearly marked as such. This may
+include source files, build scripts and documentation.
+
+"Reserved Font Name" refers to any names specified as such after the
+copyright statement(s).
+
+"Original Version" refers to the collection of Font Software
+components as distributed by the Copyright Holder(s).
+
+"Modified Version" refers to any derivative made by adding to,
+deleting, or substituting -- in part or in whole -- any of the
+components of the Original Version, by changing formats or by porting
+the Font Software to a new environment.
+
+"Author" refers to any designer, engineer, programmer, technical
+writer or other person who contributed to the Font Software.
+
+PERMISSION & CONDITIONS
+Permission is hereby granted, free of charge, to any person obtaining
+a copy of the Font Software, to use, study, copy, merge, embed,
+modify, redistribute, and sell modified and unmodified copies of the
+Font Software, subject to the following conditions:
+
+1) Neither the Font Software nor any of its individual components, in
+Original or Modified Versions, may be sold by itself.
+
+2) Original or Modified Versions of the Font Software may be bundled,
+redistributed and/or sold with any software, provided that each copy
+contains the above copyright notice and this license. These can be
+included either as stand-alone text files, human-readable headers or
+in the appropriate machine-readable metadata fields within text or
+binary files as long as those fields can be easily viewed by the user.
+
+3) No Modified Version of the Font Software may use the Reserved Font
+Name(s) unless explicit written permission is granted by the
+corresponding Copyright Holder. This restriction only applies to the
+primary font name as presented to the users.
+
+4) The name(s) of the Copyright Holder(s) or the Author(s) of the Font
+Software shall not be used to promote, endorse or advertise any
+Modified Version, except to acknowledge the contribution(s) of the
+Copyright Holder(s) and the Author(s) or with their explicit written
+permission.
+
+5) The Font Software, modified or unmodified, in part or in whole,
+must be distributed entirely under this license, and must not be
+distributed under any other license. The requirement for fonts to
+remain under this license does not apply to any document created using
+the Font Software.
+
+TERMINATION
+This license becomes null and void if any of the above conditions are
+not met.
+
+DISCLAIMER
+THE FONT SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT
+OF COPYRIGHT, PATENT, TRADEMARK, OR OTHER RIGHT. IN NO EVENT SHALL THE
+COPYRIGHT HOLDER BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+INCLUDING ANY GENERAL, SPECIAL, INDIRECT, INCIDENTAL, OR CONSEQUENTIAL
+DAMAGES, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+FROM, OUT OF THE USE OR INABILITY TO USE THE FONT SOFTWARE OR FROM
+OTHER DEALINGS IN THE FONT SOFTWARE.

assets/Noto_Color_Emoji/Noto-COLRv1.ttf

@@ -198,7 +198,7 @@ const _squareEmojiSize = 17.0;
 ///
 /// Determined experimentally:
 ///   <https://github.com/zulip/zulip-flutter/pull/410#discussion_r1402808701>
-// TODO(#404) Actually bundle Noto Color Emoji with the app. Some Android
+// TODO Actually use Noto Color Emoji. Some Android
 //   phones use Noto Color Emoji automatically, and some don't; e.g., Samsung
 //   has its own emoji font:
 //     <https://github.com/zulip/zulip-flutter/pull/410#discussion_r1408403111>

lib/widgets/emoji_reaction.dart

@@ -107,10 +107,27 @@ flutter:
   uses-material-design: true
 
   assets:
+    - assets/Noto_Color_Emoji/LICENSE
     - assets/Source_Code_Pro/LICENSE.md
     - assets/Source_Sans_3/LICENSE.md
 
   fonts:
+    # Google's emoji font. (Web uses these emoji for the "Google" emojiset.)
+    #
+    # This should always be used under a condition that excludes iOS.
+    # iOS doesn't support this font in any of its available formats,
+    # and if we use it on iOS (whether as a primary font or a fallback)
+    # we'll get blank spaces where we could have had Apple-style emojis.
+    #
+    # Also, in text that might contain non-emoji glyphs, this should
+    # always come after a non-emoji font in the chain of font-family
+    # fallbacks. Letting this font handle e.g. space characters will
+    # make text look weird.
+    # TODO don't bundle this on iOS; it wastes several MB because it's unused.
+    - family: Noto Color Emoji
+      fonts:
+        - asset: assets/Noto_Color_Emoji/Noto-COLRv1.ttf
+
     - family: Source Code Pro
       fonts:
         - asset: assets/Source_Code_Pro/SourceCodeVF-Upright.otf