fix: remove comments from blocks contained within parens (#269)

Fixes decaffeinate/decaffeinate#1181

Author: alangpierce

src/mappers/mapParens.ts

@@ -1,4 +1,6 @@
-import { Block, Parens } from 'decaffeinate-coffeescript/lib/coffee-script/nodes';
+import {
+  Block, Comment, Parens
+} from 'decaffeinate-coffeescript/lib/coffee-script/nodes';
 import { Node, SeqOp } from '../nodes';
 import ParseContext from '../util/ParseContext';
 import mapAny from './mapAny';
@@ -9,6 +11,7 @@ export default function mapParens(context: ParseContext, node: Parens): Node {
   }
 
   let { expressions } = node.body;
+  expressions = expressions.filter((expr) => !(expr instanceof Comment));
 
   if (expressions.length === 1) {
     return mapAny(context, expressions[0]);

test/examples/comment-in-parenthesized-block/input.coffee

@@ -0,0 +1,4 @@
+() -> (
+  ###yo###
+  a
+)

test/examples/comment-in-parenthesized-block/output.json

@@ -0,0 +1,49 @@
+{
+  "body": {
+    "column": 1,
+    "end": 24,
+    "inline": false,
+    "line": 1,
+    "raw": "() -> (\n  ###yo###\n  a\n)",
+    "start": 0,
+    "statements": [
+      {
+        "body": {
+          "column": 7,
+          "end": 24,
+          "inline": true,
+          "line": 1,
+          "raw": "(\n  ###yo###\n  a\n)",
+          "start": 6,
+          "statements": [
+            {
+              "column": 3,
+              "data": "a",
+              "end": 22,
+              "line": 3,
+              "raw": "a",
+              "start": 21,
+              "type": "Identifier"
+            }
+          ],
+          "type": "Block"
+        },
+        "column": 1,
+        "end": 24,
+        "line": 1,
+        "parameters": [
+        ],
+        "raw": "() -> (\n  ###yo###\n  a\n)",
+        "start": 0,
+        "type": "Function"
+      }
+    ],
+    "type": "Block"
+  },
+  "column": 1,
+  "end": 25,
+  "line": 1,
+  "raw": "() -> (\n  ###yo###\n  a\n)\n",
+  "start": 0,
+  "type": "Program"
+}