net/http: WASM Roundtripper crash when using "no-cors" mode [1.11 backport]

[gopherbot]

@FiloSottile requested issue #27196 to be considered for backport to the next 1.11 minor release.

@gopherbot please file this to be considered for backport to 1.11.

@johanbrandhorst please make a cherry-pick CL once your change is merged in master.

[johanbrandhorst]

I will fix this :)

[gopherbot]

Change https://golang.org/cl/136915 mentions this issue: [release-branch.go1.11] net/http: ensure null body in Fetch response is not read

[gopherbot]

Closed by merging b5ed6ec to release-branch.go1.11.