According to the spec data segments are allowed even if the memory size
is zero. However, if one of the data segments has a length greater than
0, then module instantiation should fail.

I also changed the exception type in LoadDataSegments to TypeError,
because that's the exception type for all exceptions which can happen
during instantiation.

R=titzer@chromium.org, rossberg@chromium.org
TEST=cctest/test-run-wasm-module/EmptyMemoryEmptyDataSegment, cctest/test-run-wasm-module/EmptyMemoryNonEmptyDataSegment

Review-Url: https://codereview.chromium.org/2483053005
Cr-Commit-Position: refs/heads/master@{#40922}