fix(rest-spread): Do not require Symbol.iterator for strings (#9794)

packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-rest/parameters-exec/exec.js

@@ -0,0 +1,9 @@
+function sum(x, y, z) {
+  return x + y + z;
+}
+function test() {
+  var args = arguments;
+  return sum(...args);
+}
+
+expect(test(1, 2, 3)).toBe(6);

packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-rest/parameters-exec/options.json

@@ -0,0 +1,3 @@
+{
+  "plugins": ["proposal-object-rest-spread"]
+}

packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-spread/string-exec/exec.js

@@ -0,0 +1,3 @@
+expect([...'']).toHaveLength(0);
+expect([...'abc']).toHaveLength(3);
+expect([...'def']).toMatchObject(['d','e','f']);