ReadableStreamBytesConsumer should check read results

ReadableStreamBytesConsumer expected that the results from
ReadableStreamReaderDefaultRead should be Promise<Object> because that
is provided from ReadableStream provided by blink, but it's possible to
inject arbitrary values with the promise assimilation.

This CL adds additional checks for such injection.

TBR=yhirano@chromium.org

(cherry picked from commit 7712d138374a92c4d2f3b05cdc86d1a7a523702b)

Bug: 840320
Change-Id: I7b3c6a8bfcf563dd860b133ff0295dd7a5d5fea5
Reviewed-on: https://chromium-review.googlesource.com/1049413
Commit-Queue: Yutaka Hirano <yhirano@chromium.org>
Reviewed-by: Adam Rice <ricea@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#556751}
Reviewed-on: https://chromium-review.googlesource.com/1062992
Reviewed-by: Yutaka Hirano <yhirano@chromium.org>
Cr-Commit-Position: refs/branch-heads/3396@{#620}
Cr-Branched-From: 9ef2aa869bc7bc0c089e255d698cca6e47d6b038-refs/heads/master@{#550428}
2 files changed