Functionality for allocating 'x' bytes with repeated GC.

[sigurdm]

In src/vm/process.cc we have

LargeInteger* Process::NewIntegerWithGC(int64 value) {
  Object* result = NewInteger(value);
  if (result->IsRetryAfterGCFailure()) {
    program()->CollectGarbage();
    result = NewInteger(value);
    if (result->IsRetryAfterGCFailure()) {
      program()->CollectGarbage();
      result = NewInteger(value);
    }
  }
  return LargeInteger::cast(result);
}

It seems fragile to rely on the behaviour of trying GC'ing twice.
Better it would be to ask the gc to free at least x bytes, and let it do as many collections as necessary.

@DmitryOlshansky-google