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 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 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.
