A new page has been created for viewing assets. This replaces the old
`selectedToken` state, which previously would augment the home page
to show token-specific information.
The new asset page shows the standard token overview as seen previously
on the home page, plus a history filtered to show just transactions
relevant to that token.
The actions that were available in the old token list menu have been
moved to a "Token Options" menu that mirrors the "Account Options"
menu.
The `selectedTokenAddress` state has been removed, as it is no longer
being used for anything.
`getMetaMetricState` has been renamed to `getBackgroundMetaMetricState`
because its sole purpose is extracting data from the background state
to send metrics from the background. It's not really a selector, but
it was convenient for it to use the same selectors the UI uses to
extract background data, so I left it there for now.
A new Redux store has been added to track state related to browser history.
The most recent "overview" page (i.e. the home page or the asset page) is
currently being tracked, so that actions taken from the asset page can return
the user back to the asset page when the action has finished.
The `AccountDetailsDropdown` component has been rewritten to use the
new `Menu` component, and to follow the latest designs.
This should be functionally equivalent. A couple of the icons have
changed, but that's about it.
Support for a subtitle was added to `MenuItem` to support the `origin`
subtitle used for the explorer link for custom RPC endpoints.
A few adjustments were required to `test/helper.js` to accommodate
the use of `Menu` from a JSDOM context (this is the first time it's
been used in a unit test). A `popover-content` element was added to the
fake DOM, and another global was added that `react-popper` used
internally.
An additional driver method (`clickPoint`) was added to the e2e driver
to allow clicking the background behind the menu to dismiss it. This
wasn't possible using the `clickElement` method, because that method
would refuse to click an obscured element. The only non-obscured
element to click was the menu backdrop, and that didn't work either
because the center was obscured by the menu (Selenium clicks the center
of whichever element is targeted).