- some pdf use some fonts which are not embedded or they don't have any width array or don't have any css info (e.g. for standard fonts or Arial).
- so add widths arrays for Liberation fonts in order to compute the ones for other fonts in using scale factors array.
- partial fix for https://bugzilla.mozilla.org/show_bug.cgi?id=1716980;
- some pdf can contain an invalid font family (e.g. 'Windings 3') so in this case remove the space;
- the font family in typeface attribute doesn't always match the one defined in the FontDescriptor dictionary.
- I thought it was possible to rely on browser layout engine to handle layout stuff but it isn't possible
- mainly because when a contentArea overflows, we must continue to layout in the next contentArea
- when no more contentArea is available then we must go to the next page...
- we must handle breakBefore and breakAfter which allows to "break" the layout to go to the next container
- Sometimes some containers don't provide their dimensions so we must compute them in order to know where to put
them in their parents but to compute those dimensions we need to layout the container itself...
- See top of file layout.js for more explanations about layout.
- fix few bugs in other places I met during my work on layout.
With the previous patch this functionality is now *only* accessed on the worker-thread, hence it's no longer necessary to include it in the *built* `pdf.js` file.
- the parser is base on a class extending XMLParserBase
- it handle xml namespaces:
* each namespace is assocated with a builder
* builder builds nodes belonging to the namespace
* when a node is inserted in the parent namespace compatibility is checked (if required)
- to avoid name collision between xml names and object properties, use Symbol.
