[wptrunner] Report crash when WebDriver browser is not alive

This aligns with how the base class `TimedRunner` differentiates
`CRASH` from other failure modes [0].

An `InvalidSessionIdException` after a browser death (e.g., [1]) is now
coerced to `CRASH`, not the generic `INTERNAL-ERROR` for harness
exceptions.

Fixes web-platform-tests#39617 and https://crbug.com/41485463.

[0]: https://github.com/web-platform-tests/wpt/blob/c338ceff/tools/wptrunner/wptrunner/executors/base.py#L216-L231
[1]: https://github.com/web-platform-tests/wpt/blob/c338ceff/tools/wptrunner/wptrunner/executors/base.py#L773

tools/wptrunner/wptrunner/executors/base.py

@@ -313,7 +313,7 @@ def run_test(self, test):
             result = self.do_test(test)
         except Exception as e:
             exception_string = traceback.format_exc()
-            message = f"Exception in TextExecutor.run:\n{exception_string}"
+            message = f"Exception in TestExecutor.run:\n{exception_string}"
             self.logger.warning(message)
             result = self.result_from_exception(test, e, exception_string)
 

tools/wptrunner/wptrunner/executors/executorwebdriver.py

@@ -539,7 +539,9 @@ def run_func(self):
             self.result = True, self.func(self.protocol, self.url, self.timeout)
         except (error.TimeoutException, error.ScriptTimeoutException):
             self.result = False, ("EXTERNAL-TIMEOUT", None)
-        except (socket.timeout, error.UnknownErrorException):
+        except socket.timeout:
+            # Checking if the browser is alive below is likely to hang, so mark
+            # this case as a CRASH unconditionally.
             self.result = False, ("CRASH", None)
         except Exception as e:
             if (isinstance(e, error.WebDriverException) and
@@ -548,11 +550,12 @@ def run_func(self):
                 # workaround for https://bugs.chromium.org/p/chromedriver/issues/detail?id=2001
                 self.result = False, ("EXTERNAL-TIMEOUT", None)
             else:
+                status = "INTERNAL-ERROR" if self.protocol.is_alive() else "CRASH"
                 message = str(getattr(e, "message", ""))
                 if message:
                     message += "\n"
                 message += traceback.format_exc()
-                self.result = False, ("INTERNAL-ERROR", message)
+                self.result = False, (status, message)
         finally:
             self.result_flag.set()