previously, when a fenced code block was in the second paragraph of a li...

previously, when a fenced code block was in the second paragraph of a list, marked would not respect the spacing of the code block in gfm mode.  This fixes that bug.
Sorry, just saw this.  Most of the tests get rid of whitespace, but whitespace is causing the problem that my pull request is fixing, so I didn't replace whitespace for my test's file.