* Transition to Hybrid lib/txt and blink text system.

* Revert "Enable line join styles and miter limit. (#3777)"

This reverts commit 5403f65b.

* Revert "Revert "Update switches to use StringView." (#3784)"

This reverts commit 80f039ff.

* Revert "Initial integration of libtxt with Flutter alongside Blink. (#3771)"

This reverts commit c548c65b.

Fixes https://github.com/flutter/flutter/issues/7723

Added a Paragraph.didExceedMaxLines property to query when this occurs.

Needed for https://github.com/flutter/flutter/issues/7271

Also fix 'ellipsis' overflow handling to work for multiline text.

Fixes https://github.com/flutter/flutter/issues/7271

The RenderView destructor does not delete its descendants.
RenderObject::destroy must be called to delete the object tree along with
other cleanup tasks.

Also associate a CustomFontData with dynamically loaded fonts in order to get
the desired FontDataCache behavior at RenderObject::destroy time.

This enables text span styles to inherit attributes from the paragraph style

See https://github.com/flutter/flutter/issues/4478

This patch makes three API changes:

 * The dart:ui library now always communicates in physical pixels. The
   framework is responsible for converting to whatever logical coordinate
   system it wishes to use.
 * The textBaselien property is now on TextStyle rather than ParagraphStyle,
   which will let us choose which baseline to use on a per-span basis rather
   than on a per-paragraph basis.
 * This patch also removes the old MojoServices function endpoints.

Fixes https://github.com/flutter/flutter/issues/3779
Fixes https://github.com/flutter/flutter/issues/1360

We can now use the real thing on Fuchsia.

We don't yet have support for text on Fuchsia. This patch add stub
implementations of Paragraph and ParagraphBuilder so that Flutter apps
that use text don't error out. Instead, the text is 0x0 and invisible.

Also, teach MojoServices not to crash if it hasn't been created by the
time Dart tries to use it.

Now lib/ui depends on sky/engine rather than the reverse.