CSS grammar not injected for custom styled-components #634

Prerequisites

• Put an X between the brackets on this line if you have done all of the following:
  • Reproduced the problem in Safe Mode: http://flight-manual.atom.io/hacking-atom/sections/debugging/#using-safe-mode
  • Followed all applicable steps in the debugging guide: http://flight-manual.atom.io/hacking-atom/sections/debugging/
  • Checked the FAQs on the message board for common solutions: https://discuss.atom.io/c/faq
  • Checked that your issue isn't already filed: https://github.com/issues?utf8=✓&q=is%3Aissue+user%3Aatom
  • Checked that there is not already an Atom package that provides the described functionality: https://atom.io/packages

Description

The CSS grammar is not properly injected for styled-components using custom components.

Steps to Reproduce

The following correctly syntax highlights:

const TestComponent = styled.div`
	h1 {
		color: green;
	}
`;

The following does not correctly syntax highlight:

const TestComponent = styled(UnstyledComponent)`
	h1 {
		color: green;
	}
`;

Versions

$ atom --version
Atom    : 1.34.0
Electron: 2.0.16
Chrome  : 61.0.3163.100
Node    : 8.9.3

$ apm --version
apm  2.1.3
npm  6.2.0
node 8.9.3 x64
atom 1.34.0
python 2.7.15
git 2.20.1