Drop trailing whitespace after all newlines.

packages/babel-generator/src/buffer.js

@@ -58,6 +58,9 @@ export default class Buffer {
    */
 
   queue(str: string): void {
+    // Drop trailing spaces when a newline is inserted.
+    if (str === "\n") while (this._queue.length > 0 && SPACES_RE.test(this._queue[0][0])) this._queue.shift();
+
     const { line, column, filename } = this._sourcePosition;
     this._queue.unshift([str, line, column, filename]);
   }
@@ -86,10 +89,6 @@ export default class Buffer {
     }
   }
 
-  removeTrailingSpaces(): void {
-    while (this._queue.length > 0 && SPACES_RE.test(this._queue[0][0])) this._queue.shift();
-  }
-
   removeTrailingNewline(): void {
     if (this._queue.length > 0 && this._queue[0][0] === "\n") this._queue.shift();
   }

packages/babel-generator/src/printer.js

@@ -167,7 +167,6 @@ export default class Printer {
     if (this.endsWith("{\n") || this.endsWith(":\n")) i--;
     if (i <= 0) return;
 
-    this._buf.removeTrailingSpaces();
     for (let j = 0; j < i; j++) {
       this._newline();
     }

packages/babel-generator/test/fixtures/edgecase/return-with-retainlines-option/expected.js

@@ -6,6 +6,6 @@ function foo(l) {
 
 function foo() {
   return (
-    1 && 2 || 
+    1 && 2 ||
     3);
 }

packages/babel-generator/test/fixtures/parentheses/terminator-break/expected.js

@@ -5,7 +5,7 @@ function foo() {
 }
 
 function foo() {
-  return(
+  return (
     // foobar
     "bar"
   );