pprof: Channel error on amd64 and arm64 with web UI

Please answer these questions before submitting your issue. Thanks!

### What version of pprof are you using?

If you are using pprof via `go tool pprof`, what's your `go env` output?
If you run pprof from GitHub, what's the Git revision?

GO111MODULE=""
GOARCH="amd64"
GOBIN=""
GOCACHE="/home/xiaji01/.cache/go-build"
GOENV="/home/xiaji01/.config/go/env"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOINSECURE=""
GONOPROXY=""
GONOSUMDB=""
GOOS="linux"
GOPATH="/home/xiaji01/.go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/home/xiaji01/src/bench/go.x86"
GOSUMDB="sum.golang.org"
GOTMPDIR="/home/xiaji01/data/depot/tmpdir"
GOTOOLDIR="/home/xiaji01/src/bench/go.x86/pkg/tool/linux_amd64"
GCCGO="gccgo"
AR="ar"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD="/home/xiaji01/src/bench/go.x86/src/go.mod"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/home/xiaji01/data/depot/tmpdir/go-build568507879=/tmp/go-build -gno-record-gcc-switches"

### What operating system and processor architecture are you using?
$ cat /proc/version
Linux version 4.4.0-154-generic (buildd@lgw01-amd64-049) (gcc version 5.4.0 20160609 (Ubuntu 5.4.0-6ubuntu1~16.04.10) ) #181-Ubuntu SMP Tue Jun 25 05:29:03 UTC 2019

$ lscpu
Architecture: x86_64
CPU op-mode(s): 32-bit, 64-bit
Byte Order: Little Endian

### What did you do?

If possible, provide a recipe for reproducing the error.
Attaching a profile you are trying to analyze is good.

go tool pprof -http=127.0.0.1:2222

### What did you expect to see?

everything works fine

### What did you see instead?

browser (firefox) crashes, and the following error message were shown in server side:

Serving web UI on http://127.0.0.1:2222
ExceptionHandler::GenerateDump cloned child 25517
ExceptionHandler::SendContinueSignalToChild sent continue signal to child
ExceptionHandler::WaitForContinueSignal waiting for continue signal...
[Parent 25275, Gecko_IOThread] WARNING: pipe error (52): Connection reset by peer: file /build/firefox-ubqoiK/firefox-67.0.4+build1/ipc/chromium/src/chrome/common/ipc_channel_posix.cc, line 357
[Parent 25275, Gecko_IOThread] WARNING: pipe error (54): Connection reset by peer: file /build/firefox-ubqoiK/firefox-67.0.4+build1/ipc/chromium/src/chrome/common/ipc_channel_posix.cc, line 357

###!!! [Parent][MessageChannel] Error: (msgtype=0x1F0088,name=PBrowser::Msg_Destroy) Channel error: cannot send/recv