Enforce braces after `if`/etc (#1719)

See https://github.com/prettier/prettier/pull/1718#discussion_r118382742

.eslintrc.js

@@ -8,6 +8,7 @@ module.exports = {
   extends: ["eslint:recommended"],
   plugins: ["prettier"],
   rules: {
+    curly: "error",
     "no-console": "off",
     "no-inner-declarations": "off",
     "no-var": "error",

src/fast-path.js

@@ -27,8 +27,9 @@ FastPath.from = function(obj) {
     // lightweight FastPath [..., name, value] stacks.
     const copy = Object.create(FastPath.prototype);
     const stack = [obj.value];
-    for (let pp; (pp = obj.parentPath); obj = pp)
+    for (let pp; (pp = obj.parentPath); obj = pp) {
       stack.push(obj.name, pp.value);
+    }
     copy.stack = stack.reverse();
     return copy;
   }

src/printer.js

@@ -1369,9 +1369,10 @@ function genericPrintNoParens(path, options, print, args) {
     case "CatchClause":
       parts.push("catch (", path.call(print, "param"));
 
-      if (n.guard)
+      if (n.guard) {
         // Note: esprima does not recognize conditional catch clauses.
         parts.push(" if ", path.call(print, "guard"));
+      }
 
       parts.push(") ", path.call(print, "body"));
 

src/util.js

@@ -1,7 +1,7 @@
 "use strict";
 
 function isExportDeclaration(node) {
-  if (node)
+  if (node) {
     switch (node.type) {
       case "ExportDeclaration":
       case "ExportDefaultDeclaration":
@@ -11,6 +11,7 @@ function isExportDeclaration(node) {
       case "ExportAllDeclaration":
         return true;
     }
+  }
 
   return false;
 }