Add parenthesis around class expression when left side of call expression (#409)

Fixes #402

tests/classes/__snapshots__/jsfmt.spec.js.snap

@@ -87,6 +87,13 @@ exports[`test binary.js 1`] = `
 "
 `;
 
+exports[`test call.js 1`] = `
+"(class {})(class {});
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+(class {})(class {});
+"
+`;
+
 exports[`test class_shapes.js 1`] = `
 "/* @flow */
 

tests/classes/call.js

@@ -0,0 +1 @@
+(class {})(class {});