Remove unnecessary quotes when using when using fat arrow attributes binding.

[michaelolof]

So i think this is alot cleaner:

Current Way:

/** @VueLiteralCompiler Template */
const template = app => `
   <button @click="${ app.doSomething() }"></button>
`;

Proposed Way:

/** @VueLiteralCompiler Template */
const template = app => `
   <button @click=${ app.doSomething() }></button>
`;