Add test for bad template string parsing

test/compress/issue-926.js

@@ -0,0 +1,9 @@
+template_strings: {
+    input: {
+        foo(
+            `<span>${contents}</span>`,
+            `<a href="${url}">${text}</a>`
+        );
+    }
+    expect_exact: "foo(`<span>${contents}</span>`,`<a href=\"${url}\">${text}</a>`);"
+}