Do not put trailing commas for function declaration in es5 mode (#791)

Fixes #789

src/printer.js

@@ -1981,7 +1981,7 @@ function printFunctionParams(path, print, options) {
       options.tabWidth,
       concat([softline, join(concat([",", line]), printed)])
     ),
-    ifBreak(canHaveTrailingComma && shouldPrintComma(options) ? "," : ""),
+    ifBreak(canHaveTrailingComma && shouldPrintComma(options, "all") ? "," : ""),
     softline,
     ")"
   ]);

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

@@ -1,5 +1,122 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
+exports[`es5.js 1`] = `
+"function send_single_email(
+  app,
+  email_id,
+  email_address,
+  subject,
+  html,
+  reply_to
+) {
+  send_single_email_implementation(  app,
+  email_id,
+  email_address,
+  subject,
+  html,
+  reply_to);
+  return \\"nothing\\";
+}
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+function send_single_email(
+  app,
+  email_id,
+  email_address,
+  subject,
+  html,
+  reply_to
+) {
+  send_single_email_implementation(
+    app,
+    email_id,
+    email_address,
+    subject,
+    html,
+    reply_to
+  );
+  return \\"nothing\\";
+}
+"
+`;
+
+exports[`es5.js 2`] = `
+"function send_single_email(
+  app,
+  email_id,
+  email_address,
+  subject,
+  html,
+  reply_to
+) {
+  send_single_email_implementation(  app,
+  email_id,
+  email_address,
+  subject,
+  html,
+  reply_to);
+  return \\"nothing\\";
+}
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+function send_single_email(
+  app,
+  email_id,
+  email_address,
+  subject,
+  html,
+  reply_to,
+) {
+  send_single_email_implementation(
+    app,
+    email_id,
+    email_address,
+    subject,
+    html,
+    reply_to,
+  );
+  return \\"nothing\\";
+}
+"
+`;
+
+exports[`es5.js 3`] = `
+"function send_single_email(
+  app,
+  email_id,
+  email_address,
+  subject,
+  html,
+  reply_to
+) {
+  send_single_email_implementation(  app,
+  email_id,
+  email_address,
+  subject,
+  html,
+  reply_to);
+  return \\"nothing\\";
+}
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+function send_single_email(
+  app,
+  email_id,
+  email_address,
+  subject,
+  html,
+  reply_to
+) {
+  send_single_email_implementation(
+    app,
+    email_id,
+    email_address,
+    subject,
+    html,
+    reply_to
+  );
+  return \\"nothing\\";
+}
+"
+`;
+
 exports[`function-calls.js 1`] = `
 "const a = (param1, param2, param3) => {}
 
@@ -447,14 +564,14 @@ o = {
 
 function supersupersupersuperLongF(
   supersupersupersuperLongA,
-  supersupersupersuperLongB,
+  supersupersupersuperLongB
 ) // Comment
 {
   a;
 }
 function supersupersupersuperLongF(
   supersupersupersuperLongA,
-  supersupersupersuperLongB,
+  supersupersupersuperLongB
 ) // Comment
 {
   a;

tests/trailing_comma/es5.js

@@ -0,0 +1,16 @@
+function send_single_email(
+  app,
+  email_id,
+  email_address,
+  subject,
+  html,
+  reply_to
+) {
+  send_single_email_implementation(  app,
+  email_id,
+  email_address,
+  subject,
+  html,
+  reply_to);
+  return "nothing";
+}