Bug 329451 – [WebDriver BiDi] input.performActions: refresh the target frame's viewport during an action sequence

• Status: NEW
• Component: WebDriver

[Razvan Caliman]

Follow-up for bug 326378

WebAutomationSession::runBidiInteractionSequence gets the target frame's viewport (its origin and size in main-frame coordinates) only once, before the action sequence starts. The whole sequence then runs with that SimulatedInputViewport.

If an earlier action scrolls the page, re-lays it out or moves the frame, later actions in the same sequence use a stale viewport. That breaks:
  - viewport-origin moves in an iframe, which land at the old frame origin;
  - "move target out of bounds" checks, which test against the old viewport size.
  
Fix: get the viewport again before each tick (or each viewport-origin move), or have the web process resolve viewport coordinates when it dispatches the action.

Reported in review of https://github.com/WebKit/WebKit/pull/75927#discussion_r4373370438