If '\r' appears in an inline <style> element, libhubbub splits the text nodes
there, creating multiple text children. The inline style logic assumed that
each <style> element had only one child.
The logic was moved to trigger when the style element is finished parsing
completely (including the children), and then the children are concatenated
before sending it to the parser.
script caches last loaded url -- currently no caching policy
naive caching of render layers for near-instant forward/back
handling evicted pipelines is currently broken
