Fix order of top nodes (comments and imports)

[mgreter]

Fixes #1080

[coveralls]

Coverage decreased (-0.01%) to 80.26% when pulling 6f50613 on mgreter:bugfix/issue_1080 into 89338a7 on sass:master.

[HamptonMakes]

Interestingly, the test for 1080 passes already... without this commit!

[xzyfer]

Might be a sass-spec issue because the output is certainly incorrectly

$ sassc test.scss
/** comment 1 */
@import url("import-1");
@import url("import-2");
/** comment 2 */
/** comment 3 */
foo {
  bar: baz; }

$ sass test.scss
/** comment 1 */
@import url("import-1");
/** comment 2 */
@import url("import-2");
/** comment 3 */
foo {
  bar: baz; }

[HamptonMakes]

hmmm... what the hell is wrong with my setup...

[coveralls]

Coverage decreased (-0.01%) to 80.26% when pulling 94cbc82 on mgreter:bugfix/issue_1080 into 9ad775f on sass:master.