Implement SVG rendering

[wojtekmaj]

SVG rendering is starting to be supported by PDF.js, so we should push forward as well. This technique gives us several advantages.

• Improved rendering performance
• Improved accessibility
• TextLayers are gone; we're rendering text once and for good

To-dos

PoC stage

• Investigate possibility of SVG rendering
• Implement proof of concept

Alpha stage (separate branch)

• Introduce renderMode flag to opt-in for SVG rendering
• Resolve React-PDF SVG rendering issues
• Report and monitor PDF.js SVG rendering issues
  • core-js placed in devDependencies core-js placed in dev-dependencies instead of dependencies mozilla/pdf.js#8890
  • SVG is ignoring viewport rotation
  • <svg:rect> attribute height: A negative value is not valid. ("-94.04")

Beta stage

• Wait for Mozilla to announce SVG rendering production-ready
• Switch default renderMode to SVG

Release statge

• Resolve React-PDF reported SVG rendering issues

Future

• Get rid of Canvas rendering altogether