This is an export which looks like `export {} from "module"`, and
although it doesn't have any real export entries it should still add
"module" to the required modules to load.
We didn't initially upgrade because it started to (incorrectly) see
files as strict mode and chokes on things that then would be syntax
errors - but we're starting to fall behind a bit, so I'd rather put
these files on the ignore list instead.
For example, "property.br\u{64}wn" should resolve to "property.brown".
To support this behavior, this commit changes the Token class to hold
both the evaluated identifier name and a view into the original source
for the unevaluated name. There are some contexts in which identifiers
are not allowed to contain Unicode escape sequences; for example, export
statements of the form "export {} from foo.js" forbid escapes in the
identifier "from".
The test file is added to .prettierignore because prettier will replace
all escaped Unicode sequences with their unescaped value.
