Prevent multiple return statements in a loop when replacing expressions (#5030)

packages/babel-plugin-transform-do-expressions/test/fixtures/do-expressions/while-if/actual.js

@@ -0,0 +1,10 @@
+let p
+let a = do {
+  while (p = p.parentPath) {
+    if (a) {
+      'a'
+    } else {
+      'b'
+    }
+  }
+};

packages/babel-plugin-transform-do-expressions/test/fixtures/do-expressions/while-if/expected.js

@@ -0,0 +1,13 @@
+let p;
+let a = function () {
+  var _ret;
+
+  while (p = p.parentPath) {
+    if (a) {
+      _ret = 'a';
+    } else {
+      _ret = 'b';
+    }
+  }
+  return _ret;
+}();