Issue #1422614 by droplet, rob.black, nod_: Drop Firefox 3.6 support in Drupal core.

core/modules/block/block.admin.css

core/modules/contextual/contextual.theme-rtl.css

core/modules/contextual/contextual.theme.css

core/modules/overlay/overlay-child-rtl.css

core/modules/overlay/overlay-child.css

core/modules/shortcut/shortcut.theme-rtl.css

core/modules/shortcut/shortcut.theme.css

...pletest/files/css_test_files/css_input_without_import.css

...css_test_files/css_input_without_import.css.optimized.css

...s_test_files/css_input_without_import.css.unoptimized.css

core/modules/system/system.theme.css

core/modules/toolbar/toolbar.css

core/themes/bartik/color/preview.css

core/themes/bartik/css/style.css

core/themes/seven/jquery.ui.theme.css

core/themes/seven/style.css