Fix remaining RequestDatum tests.

Fix remaining RequestDatum tests.

There were a few problems:

- An expression like "x is List<Foo>" doesn't guarantee that every
  element of x is of type Foo.  We need to check item by item.
  Similar for maps.

- InvalidParameterResponseMatcher was failing to account for the fact
  that the response gets wrapped in a RequestFailure object.

- Tests weren't calling setUp().

R=brianwilkerson@google.com

Committed: https://code.google.com/p/dart/source/detail?r=36237

[Brian Wilkerson, 2014-05-15 18:11:48]

LGTM

[Paul Berry, 2014-05-15 20:03:57]

Committed patchset #1 manually as r36237 (presubmit successful).

[danrubel, 2014-05-15 20:22:03]

lgtm