Build warnings related to Sass have been reduced by dynamically
importing `gulp-sass` and `sass-compiler` at the point where it's first
used. This ensures that the four Dart-related build warnings are only
emitted for the build process that is actually running Sass, rather
than by _every_ build process.
The `devMode` parameter being passed to the `buildScss` function was
not being used. The `buildScss` function was declared _inside_ the
function in which it is invoked, so the `devMode` variable is already
in scope - it doesn't need to be passed in.
The `styles:dev` step of the development build was broken in #9568 when
the `lockdown()` function from SES was introduced. One of the effects
of `lockdown()` is preventing the use of `RegExp.lastMatch`, which is
relied upon by `postcss` for parsing inline sourcemaps.
This problem has been worked around by re-arranging the build pipeline
for styles.
Firstly, the `autoprefixer` stage was moved _before_ sourcemaps were
generated. Its placement _after_ sourcemaps was a mistake in the first
place - it should have always been before they were written, so that
the sourcemaps could keep track of the changes made by `autoprefixer`.
Second, the `-rtl` sourcemap generation was moved to a separate build
pipeline. The `rtl` stage also uses `postcss`, and it must come after
the sourcemaps are written for the non-RTL styles, so splitting it into
a separate build was the only way to avoid passing in inline
sourcemaps. This does make the build slightly slower, but it also
decreases the size of the RTL sourcemaps dramatically.
Brad Decker
Mark Stacey
Etienne Dusseault
Erik Marks
Whymarrh Whitby
kumavis