* Replace css-escape-polyfill.js with escapecss.js utility module
* Add $tw.utils.escapeCSS() method and invoke that function within the
escapecss operator.
* Add test cases for the "escapecss" filter operator
* Fix $tw.boot.doesTaskMatchPlatform() so it works as expected if
a module's export.platforms contains more than one values
* Add missed files to the last commit
Default with no suffix is pre-5.1.23 behavior, escaping all Unicode
characters for maximum compatibility (avoids encoding issues). New
"rawunicode" suffix allows passing through Unicode characters U+0080
and up unchanged, for cases where you know your tools are handling
encoding correctly and you want less verbose escaping.
* add escapecss filter
this filter would allow creating valid css classes from titles containing special characters
we assign a class to an element using `encodeuricomponent[]` so that the class name is encoded
in a stylesheet we create the classname by `<title>escapecss[]` which applies the uri encoding and escapes characters that need to be escaped
* Update encodings.js
* refactor tagToCssSelector, add escapeCssSelector
* use escapeCssSelector
* escape using CSS.escape if it's available
* Update encodings.js
* revert factoring out escapeCssSelector
