Drop ambiguous MaybeHandle comparison and hashing ops.

Drop ambiguous MaybeHandle comparison and hashing ops.

The default equality comparison operators and hashing functions for
Handles are ambiguous. The intended semantics might have either been
based on Handle locations or on object identity. This is why such
operators do not exist on Handle. The same argument applies to the
MaybeHandle class as well. Comments in that regard were also added.

R=bmeurer@chromium.org

Committed: https://crrev.com/51fa9e5295f708495cbb3287987745eb70f3735f
Cr-Commit-Position: refs/heads/master@{#30468}

[Benedikt Meurer, 2015-08-31 11:12:16]

LGTM

[Michael Starzinger, 2015-08-31 11:21:25]

The CQ bit was checked by mstarzinger@chromium.org

[commit-bot: I haz the power, 2015-08-31 11:21:32]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1319383002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1319383002/1

[commit-bot: I haz the power, 2015-08-31 11:37:39]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-08-31 11:37:53]

Patchset 1 (id:??) landed as
https://crrev.com/51fa9e5295f708495cbb3287987745eb70f3735f
Cr-Commit-Position: refs/heads/master@{#30468}