Actually compute dask arrays in benchmark.

asv_bench/benchmarks/polyfit.py

@@ -18,13 +18,13 @@ def setup(self, *args, **kwargs):
  def time_polyval(self, nx, ndeg):
  x = self.xs[nx]
  c = self.coeffs[ndeg]
- xr.polyval(x, c)
+ xr.polyval(x, c).compute()
 
  @parameterized(["nx", "ndeg"], [nxs, ndegs])
  def peakmem_polyval(self, nx, ndeg):
  x = self.xs[nx]
  c = self.coeffs[ndeg]
- xr.polyval(x, c)
+ xr.polyval(x, c).compute()
 
 
 class PolyvalDask(Polyval):