Fix parenthesis in object as left-hand-side of template (#398)

Fixes #392

src/fast-path.js

@@ -417,6 +417,9 @@ FPp.needsParens = function(assumeExpressionContext) {
       if (parent.type === "ArrowFunctionExpression" && name === "body") {
         return true;
       }
+      if (parent.type === "TaggedTemplateExpression") {
+        return true;
+      }
 
     default:
       if (

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

@@ -43,6 +43,15 @@ var z = Object(123);
 "
 `;
 
+exports[`test expression.js 1`] = `
+"() => ({}\`\`);
+({})\`\`;
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+(() => ({})\`\`);
+({})\`\`;
+"
+`;
+
 exports[`test objects.js 1`] = `
 "/* @flow */
 

tests/objects/expression.js

@@ -0,0 +1,2 @@
+() => ({}``);
+({})``;