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WebDriver afb578090bc9

Updating prompt handling during user script to be consistent Section 18 of the spec states that, "When a user prompt appears, it is the task of the subsequent command to handle it." The algorithm for "Executing a function body" (Section 15.2) violates this statement, insisting that the user prompt handler be invoked during the current command, rather than by the subsequent command. Instead, we should immediately abort the execute[Async]Script command, and let the subsequent command handle the user prompt, if any.

Jim Evans