Upgrade prettier to v2

Prettier v2 has the following breaking changes:
* enforces spaces between `function` and params
* enforces trailing commas by default

lib/handlebars/runtime.js

@@ -4,13 +4,13 @@ import {
   COMPILER_REVISION,
   createFrame,
   LAST_COMPATIBLE_COMPILER_REVISION,
-  REVISION_CHANGES
+  REVISION_CHANGES,
 } from './base';
 import { moveHelperToHooks } from './helpers';
 import { wrapHelper } from './internal/wrapHelper';
 import {
   createProtoAccessControl,
-  resultIsAllowed
+  resultIsAllowed,
 } from './internal/proto-access';
 
 export function checkRevision(compilerInfo) {
@@ -73,7 +73,7 @@ export function template(templateSpec, env) {
 
     let extendedOptions = Utils.extend({}, options, {
       hooks: this.hooks,
-      protoAccessControl: this.protoAccessControl
+      protoAccessControl: this.protoAccessControl,
     });
 
     let result = env.VM.invokePartial.call(
@@ -115,15 +115,15 @@ export function template(templateSpec, env) {
 
   // Just add water
   let container = {
-    strict: function(obj, name, loc) {
+    strict: function (obj, name, loc) {
       if (!obj || !(name in obj)) {
         throw new Exception('"' + name + '" not defined in ' + obj, {
-          loc: loc
+          loc: loc,
         });
       }
       return container.lookupProperty(obj, name);
     },
-    lookupProperty: function(parent, propertyName) {
+    lookupProperty: function (parent, propertyName) {
       let result = parent[propertyName];
       if (result == null) {
         return result;
@@ -137,7 +137,7 @@ export function template(templateSpec, env) {
       }
       return undefined;
     },
-    lookup: function(depths, name) {
+    lookup: function (depths, name) {
       const len = depths.length;
       for (let i = 0; i < len; i++) {
         let result = depths[i] && container.lookupProperty(depths[i], name);
@@ -146,21 +146,21 @@ export function template(templateSpec, env) {
         }
       }
     },
-    lambda: function(current, context) {
+    lambda: function (current, context) {
       return typeof current === 'function' ? current.call(context) : current;
     },
 
     escapeExpression: Utils.escapeExpression,
     invokePartial: invokePartialWrapper,
 
-    fn: function(i) {
+    fn: function (i) {
       let ret = templateSpec[i];
       ret.decorator = templateSpec[i + '_d'];
       return ret;
     },
 
     programs: [],
-    program: function(i, data, declaredBlockParams, blockParams, depths) {
+    program: function (i, data, declaredBlockParams, blockParams, depths) {
       let programWrapper = this.programs[i],
         fn = this.fn(i);
       if (data || depths || blockParams || declaredBlockParams) {
@@ -179,13 +179,13 @@ export function template(templateSpec, env) {
       return programWrapper;
     },
 
-    data: function(value, depth) {
+    data: function (value, depth) {
       while (value && depth--) {
         value = value._parent;
       }
       return value;
     },
-    mergeIfNeeded: function(param, common) {
+    mergeIfNeeded: function (param, common) {
       let obj = param || common;
 
       if (param && common && param !== common) {
@@ -198,7 +198,7 @@ export function template(templateSpec, env) {
     nullContext: Object.seal({}),
 
     noop: env.VM.noop,
-    compilerInfo: templateSpec.compiler
+    compilerInfo: templateSpec.compiler,
   };
 
   function ret(context, options = {}) {
@@ -412,7 +412,7 @@ function executeDecorators(fn, prog, container, depths, data, blockParams) {
 }
 
 function wrapHelpersToPassLookupProperty(mergedHelpers, container) {
-  Object.keys(mergedHelpers).forEach(helperName => {
+  Object.keys(mergedHelpers).forEach((helperName) => {
     let helper = mergedHelpers[helperName];
     mergedHelpers[helperName] = passLookupPropertyOption(helper, container);
   });
@@ -420,7 +420,7 @@ function wrapHelpersToPassLookupProperty(mergedHelpers, container) {
 
 function passLookupPropertyOption(helper, container) {
   const lookupProperty = container.lookupProperty;
-  return wrapHelper(helper, options => {
+  return wrapHelper(helper, (options) => {
     return Utils.extend({ lookupProperty }, options);
   });
 }