Replace dev.w3.org with more permanent or stable urls

Replace dev.w3.org with more permanent or stable urls

* Sanitizer: dev.w3.org/html5/spec-preview
  Follows-up 8e8b15afc6.
  Use stable reference to www.w3.org/TR/html5 instead (currently
  from October 2014) instead of an old preview branch from 2012.

* parserTests: dev.w3.org/html5
  Follows-up 959aa336a1.
  Url is now a dead end. Replaced with link to a draft from around
  that time. The relevant section no longer exists in the curent
  spec as it got split off into a separate spec. Maybe this one:
  https://url.spec.whatwg.org/#percent-encoded-bytes

* Parser, HTMLIntField: dev.w3.org/html5
  Use stable reference to www.w3.org/TR/html5 instead.

* HTMLFloatField.php: dev.w3.org/html5
  Url is now a dead end. Draft from around that time:
  http://www.w3.org/TR/2011/WD-html5-20110525/common-microsyntaxes.html#real-numbers
  The section "Real numbers" no longer exists in the current spec,
  but the Infrastructure chapter has a section on floating point
  numbers that describes the same sequence now.

Change-Id: I7dcd49b6cd39785fb1b294e4eeaf39bda52337b2