feat(chrome): read the page's exceptions and navigations, and hold the picker state across them

a page navigation replaces the runtime, so the seeded picker restarted the seed's stream at its first draw on every reload and a trace could not tell a reload from a generator repeating itself. the driver now drains the main-frame navigations it saw, reports the page's buffered uncaught errors so state.exceptions is the page's list on the goja host too, and carries the picker's draw position out of v8 and back in around each decision.

internal/driver/chrome/testdata/picker-stream.html

@@ -0,0 +1,14 @@
+<!doctype html>
+<meta charset="utf-8">
+<title>picker stream</title>
+<style>
+  button { display: block; width: 120px; height: 30px; margin: 10px; }
+</style>
+<form action="" method="get">
+  <input id="entry" placeholder="what needs to be done">
+</form>
+<button id="one">one</button>
+<button id="two">two</button>
+<button id="three">three</button>
+<button id="four">four</button>
+<button id="five">five</button>