Move Gmail CSS class definitions to a new module

Allow them to be used for a new Sidebar module that will enable sidebar
toggling.

Had to switch the compiled module system to `amd` because of this error
message:

    tsconfig.json:3:3 - error TS6082: Only 'amd' and 'system' modules
    are supported alongside --outFile.

Thinking I'm going to switch to Typescript namespaces to save myself the
trouble of using a 'require' library for the AMD modules.

1 files changed, 5 insertions, 0 deletions

diff --git a/src/gmail_css_class.ts b/src/gmail_css_class.ts
new file mode 100644
index 0000000..70b91e1
--- /dev/null
+++ b/src/gmail_css_class.ts
@@ -0,0 +1,5 @@
+export type GmailCSSClass = string;
+
+export const TOOLS_PANEL: GmailCSSClass = 'bAw';
+export const SIDEBAR: GmailCSSClass = 'aeN';
+export const MESSAGE_PAGER: GmailCSSClass = 'AO';