Case: invoke load() on an element with pending promises.
Expected result: reject all the pending promises.
MozReview-Commit-ID: Kg5FHAmhF4L
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extra : rebase_source : db6dc8b32e4c67963694e295a3a7ae536bb0a912
extra : source : 2576d87906f71cf44f00bb7e447af2393587a4f6