handle runtime errors in expect_stdout

[alexlamsl]

allow test to pass if both input and expect throws the same kind of error

[alexlamsl]

https://github.com/mishoo/UglifyJS2/pull/1618/files?w=1 might make it marginally easier to review

[kzc]

At least it'll be consistent. Consider:

$ echo 'const a = 1; console.log(a++);' | node0_10_41 
1

$ echo 'const a = 1; console.log(a++);' | node421
1

$ echo 'const a = 1; console.log(a++);' | node690
[stdin]:1
const a = 1; console.log(a++);
                          ^

TypeError: Assignment to constant variable.