Changed the wording to be more consistent between `<svelte:window>`, `<svelte:body>` and `<svelte:head>`.
Chose "may only appear" over "has to appear" as the latter could be misinterpreted as a compulsory element
* add Style node, interfaces
* style-directives: add parser and runtime test
* style-directives: push styles in to styles array on Element
* style-directives: minimal ssr work
* style-directives: ssr add_styles
* style-directive: tests
* style-directives: work in progress
* obviously incorrect hard-coded color
* tweak
* style directive interface
* style-directives: get text from info in Style node
* style-directives: add_styles func in ElementWrapper
* style-directives: ssr rendering
* handle text-only style directive in tag.ts
* style-directives: handle spread styles in ssr
* style-directives: more parser tests
* style-directives: more inline tests
* style-directives: remove solo tests
* style-directives: cleanup
* style-directives: tweak spread ssr internal
* style-directives: push updater into update chunks; add dynamic test;
* remove .solo
* check for dynamic dependencies before adding update chunk
* add test of multiple styles; remove null styles;
* style-directives: docs; more tests of multiple styles
* style-directives: use camelcase
* style-directives: cleanup
* style-directives: fix mustache template case with template literal
* style-directives: use ternary
* style-directives: linting
* style-directives: remove "text" from interface
* style-directives: actually, remove StyleDirective interface entriely
* add more test, fix test for ssr
* fix lint and tidy up
* add test for css variables
* fix linting errors
Co-authored-by: pmurray73 <pmurray73@bloomberg.net>
Co-authored-by: Tan Li Hau <lhtan93@gmail.com>