.foo {
    background: linear-gradient(to right, red, green);
}

.foo {
  background: -webkit-linear-gradient(right, red, green); /* The directions of the old and new grammars are not equivalent. */
  background: linear-gradient(to right, red, green);
}

.foo {
  background: -webkit-linear-gradient(left, red, green);
  background: linear-gradient(to right, red, green);
}