Merge pull request #718 from rollup/ghi-717

Allow `sourceMapFile` as an option.

src/rollup.js

@@ -28,6 +28,7 @@ const ALLOWED_KEYS = [
 	'plugins',
 	'preferConst',
 	'sourceMap',
+	'sourceMapFile',
 	'targets',
 	'treeshake',
 	'useStrict'

test/test.js

@@ -76,7 +76,7 @@ describe( 'rollup', function () {
 			return rollup.rollup({ entry: 'x', plUgins: [] }).then( function () {
 				throw new Error( 'Missing expected error' );
 			}, function ( err ) {
-				assert.equal( err.message, 'Unexpected key \'plUgins\' found, expected one of: acorn, banner, cache, dest, entry, exports, external, footer, format, globals, indent, intro, moduleId, moduleName, noConflict, onwarn, outro, plugins, preferConst, sourceMap, targets, treeshake, useStrict' );
+				assert.equal( err.message, 'Unexpected key \'plUgins\' found, expected one of: acorn, banner, cache, dest, entry, exports, external, footer, format, globals, indent, intro, moduleId, moduleName, noConflict, onwarn, outro, plugins, preferConst, sourceMap, sourceMapFile, targets, treeshake, useStrict' );
 			});
 		});
 	});