Per SVG2, any coordinate pairs following a moveto command should be
treated as implicit lineto commands with the same absoluteness as the
moveto command.
This attribute is used to define how the viewBox should be scaled.
Previously the behaviour implemented was that of "xMidYMid meet", now
all of them work (expect none :P).
With this the Discord login backend is now correctly scaled/positioned.
This also brings our SVG code a little closer to the spec! With spec
comments and all :^)
(Minor non-visible update to layout tests)
This parses SVG transforms using the syntax from CSS Transforms
Module Level 1. Note: This looks very similar to CSS tranforms, but
the syntax is not compatible. For example, SVG rotate() is
rotate(<a> <x> <y>) where all parameters are unitless numbers whereas
CSS rotate() is rotate(<angle> unit) along with separate rotateX/Y/Z().
(At the same time AttributeParser is updated to use GenericLexer which
makes for easier string matching).
There is work needed for error handling (which AttributeParser does not
deal with very gracefully right now).
Because the result will be a float anyway get rid of the int parsing.
Also the grammar of SVG numbers matches the double parser grammar except
it can't have a sign but that should have been checked by the caller.
This is all still quite ad-hoc. Eventually these will both need to
support units (like with CSS Lengths) but for now we can continue only
using numbers.
I've chosen the name `AttributeParser` since it parses data from
attributes. Rather than duplicate the parsing of numbers and other
basic types, let's make use of this existing parsing code for parsing
the data for `<line>`, `<polyline>`, etc.
