[bash] Variable is not highlighted in heredoc

[alexr00]

From @Ash258 in microsoft/vscode#80270

#!/bin/bash
variable='whatever'
cat << END
<prtg>
	<result>
		<Channel>Memory usage</Channel>
		<Value>$variable</Value>
	</result>
</prtg>
echo "$variable"
END

Variable substitution is supported inside heredoc and variables should be highlighted as in normal string.

Bat output for comparison:

[rsese]

Thanks for the report!

Variable substitution is supported inside heredoc and variables should be highlighted as in normal string.

Looks like this works in Atom 1.40.1 on macOS 10.14.6 with Tree-sitter enabled:

Since the problem isn't an issue with Tree-sitter, we'll go ahead and close as described below.

---

As you may have heard, we are migrating from our old first-mate grammar engine to the new Tree-sitter engine. This will enable a number of new features, more consistent syntax highlighting, and better performance, among other benefits. In order to free up our limited resources, we have decided to stop maintaining the first-mate grammar when there is a built-in Tree-sitter grammar available. Since this issue applies only to the first-mate grammar, we are going to close it. Please let us know if we have misunderstood the description of the problem.