Previously, we were collapsing whitespace in Layout::TextNode and then
passed the resulting string for further processing through ChunkIterator
-> InlineLevelIterator -> InlineFormattingContext -> LineBuilder ->
LineBoxFragment -> PaintableFragment. Our painting tree is where we deal
with things like range offsets into the underlying text nodes, but since
we modified the original string, the offsets were wrong.
This changes the way we generate fragments:
* Layout::TextNode no longer collapses whitespace as part of its
stored "text for rendering", but moves this logic to ChunkIterator
which splits up this text into separate views whenever whitespace
needs to be collapsed.
* Layout::LineBox now only extends the last fragment if its end offset
is equal to the new fragment's start offset. Otherwise, there's a
gap caused by collapsing whitespace and we need to generate a
separate fragment for that in order to have a correct start offset.
Some tests need new baselines because of the fixed start offsets.
Fixes#566.
Resulting in a massive rename across almost everywhere! Alongside the
namespace change, we now have the following names:
* JS::NonnullGCPtr -> GC::Ref
* JS::GCPtr -> GC::Ptr
* JS::HeapFunction -> GC::Function
* JS::CellImpl -> GC::Cell
* JS::Handle -> GC::Root
