fix(javascript): remove that special case for class

docs/rationale.md

@@ -99,24 +99,6 @@ class HeroButtonComponent {
 }
 ```
 
-There's one exception: classes. We don't think it ever makes sense to inline the decorators for them, so they are always moved to their own line.
-
-<!-- prettier-ignore -->
-```js
-// Before running Prettier:
-@observer class OrderLine {
-  @observable price: number = 0;
-}
-```
-
-```js
-// After running Prettier:
-@observer
-class OrderLine {
-  @observable price: number = 0;
-}
-```
-
 Note: Prettier 1.14.x and older tried to automatically move your decorators, so if you've run an older Prettier version on your code you might need to manually join up some decorators here and there to avoid inconsistencies:
 
 ```js

src/language-js/printer-estree.js

@@ -117,12 +117,9 @@ function genericPrint(path, options, printPath, args) {
         options.locStart(node.decorators[0])
     )
   ) {
-    const shouldBreak =
-      node.type === "ClassExpression" ||
-      node.type === "ClassDeclaration" ||
-      hasNewlineBetweenOrAfterDecorators(node, options);
-
-    const separator = shouldBreak ? hardline : line;
+    const separator = hasNewlineBetweenOrAfterDecorators(node, options)
+      ? hardline
+      : line;
 
     path.each(decoratorPath => {
       let decorator = decoratorPath.getValue();
@@ -136,7 +133,7 @@ function genericPrint(path, options, printPath, args) {
     }, "decorators");
 
     if (parentExportDecl) {
-      decorators.unshift(hardline);
+      decorators.unshift(softline);
     }
   } else if (
     isExportDeclaration(node) &&

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

@@ -17,8 +17,7 @@ const foo =
     //
   };
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-@deco
-class Foo {}
+@deco class Foo {}
 
 @deco
 export class Bar {}

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

@@ -14,13 +14,9 @@ class Hello {}
 
 export default @decorator class {}
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-export
-@decorator
-class Foo {}
+export @decorator class Foo {}
 
-export
-@decorator
-class Bar {}
+export @decorator class Bar {}
 
 export
 @decorator
@@ -36,9 +32,7 @@ export
 @decorator
 class Hello {}
 
-export default
-@decorator
-class {}
+export default @decorator class {}
 
 `;
 

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

@@ -233,8 +233,7 @@ class Class3 {
   ) {}
 }
 
-@decorated
-class Foo {}
+@decorated class Foo {}
 
 class Bar {
   @decorated method() {}