Revert "Shell EOF derps : Chromium prebuilt"

This reverts commit 73c6ce9b676152c3be9e27b92f4d67a4c4ed8c76.
Revert "Prebuilt chromium: update script for lollipop"

This reverts commit eda4c3ab238aa20a45a3845adc7f2163a7c510e1.
Revert "vendor/omni: Fix-ups for prebuilt Chromium"

This reverts commit 9201e9bdf63700a74d24f1de7e8d5e9667f1a486.
Revert "vendor/omni: Add chromium_prebuilt.sh"

This reverts commit a9dae0ca09440735d7b7de704c83417144cdbc2f.