This is just lots of renaming.
The interface remains private, so the public API does not change, apart
from removing the definition of the Interface object to avoid
subclassing.
When the first/last color stop is not at 0%/100%, we need to start the
repeating at their offsets and not at 0%/100%.
Attached reftest demonstrates the problem.
The spec says:
"If <shape> is omitted, the ending shape defaults to a circle if the <size>
is a single <length>, and to an ellipse otherwise."
Make it so.
This is in preparation for calc(), as calc(50% - 5px) is valid CSS
but has 2 units. Instead, add a function to query a value's dimension
(so we can differentiate lengths from numbers) and add a function to
query if the value contains percentages.
Don't allow syntax like
at top left circle
but follow the spec about requiring the at <position> right before the
comma.
This is porbably because
circle at 10px 10px
could be interpreted as
circle 10px at 10px
with the now disallowed syntax, too.
Test included.
