[wasm] Correctly handle the result of WasmModule::Instantiate in the wasm-module-runner

[wasm] Correctly handle the result of WasmModule::Instantiate in the wasm-module-runner

WasmModule::Instantiate can return an empty handle if it is not possible
to instantiate the module. With this change the wasm-module-runner does
not assume anymore that WasmModule::Instantiate produces a valid handle.

BUG=chromium:648078
R=titzer@chromium.org

Committed: https://crrev.com/447de9ae5b3ca027ec741147f7bc50de438d32f4
Cr-Commit-Position: refs/heads/master@{#39629}

[ahaas, 2016-09-22 11:56:48]

The CQ bit was checked by ahaas@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2016-09-22 11:56:55]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-09-22 12:21:37]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2016-09-22 12:21:38]

Dry run: This issue passed the CQ dry run.

[titzer, 2016-09-22 14:19:55]

lgtm

[ahaas, 2016-09-22 14:21:34]

The CQ bit was checked by ahaas@chromium.org

[commit-bot: I haz the power, 2016-09-22 14:21:38]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-09-22 14:23:39]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-09-22 14:23:53]

Description was changed from

==========
[wasm] Correctly handle the result of WasmModule::Instantiate in the
wasm-module-runner

WasmModule::Instantiate can return an empty handle if it is not possible
to instantiate the module. With this change the wasm-module-runner does
not assume anymore that WasmModule::Instantiate produces a valid handle.

BUG=chromium:648078
R=titzer@chromium.org
==========

to

==========
[wasm] Correctly handle the result of WasmModule::Instantiate in the
wasm-module-runner

WasmModule::Instantiate can return an empty handle if it is not possible
to instantiate the module. With this change the wasm-module-runner does
not assume anymore that WasmModule::Instantiate produces a valid handle.

BUG=chromium:648078
R=titzer@chromium.org

Committed: https://crrev.com/447de9ae5b3ca027ec741147f7bc50de438d32f4
Cr-Commit-Position: refs/heads/master@{#39629}
==========

[commit-bot: I haz the power, 2016-09-22 14:23:54]

Patchset 1 (id:??) landed as
https://crrev.com/447de9ae5b3ca027ec741147f7bc50de438d32f4
Cr-Commit-Position: refs/heads/master@{#39629}