When assigning to an integer view of the heap an intish
value does not need to be collapsed with |0.
Similarly a floatish value does not need to be collapsed with
fround when assigned to a float view of the heap.
i32[0] = i32_1 + i32_2;  // ok
f32[0] = f32_1 + f32_2;  // ok

However, floatish values cannot be safely assigned to double
arrays.
f64[0] = f32_1 + f32_2;  // not ok

BUG= https://code.google.com/p/v8/issues/detail?id=4203
TEST=mjsunit/asm-wasm,test-asm-validator
R=aseemgarg@chromium.org,titzer@chromium.org
LOG=N

Review URL: https://codereview.chromium.org/1722473002

Cr-Commit-Position: refs/heads/master@{#34206}