Remove duplicated test files

Even if they used to test different things in the past, they are
now identical to other files.

Closes #11496
Change /bin/env to /usr/bin/env in helper python script, as it is more portable
Register new snapshots
auto merge of #15100 : rapha/rust/master, r=alexcrichton

/usr/bin/env appears to be more portable.
auto merge of #15106 : Sawyer47/rust/rm-duplicated-tests, r=alexcrichton

Even if they used to test different things in the past, they are
now identical to other files.

Closes #11496
rustc: catch non-trait methods before typeck.

Closes #3973.
rustc: catch `impl X for Y` where X is not a trait in resolve.
auto merge of #14974 : Ryman/rust/non_trait_method, r=alexcrichton

Closes #3973.
libsyntax: Disallow struct literals after `if`, `while`, `match`, and
`for...in`.

Closes #14803.

If you used a structure literal after one of these keywords, surround it
in parentheses.

[breaking-change]
auto merge of #14885 : pcwalton/rust/struct-literal-tightening, r=alexcrichton

`for...in`.

Closes #14803.

If you used a structure literal after one of these keywords, surround it
in parentheses.

[breaking-change]

r? @nick29581
auto merge of #15105 : alexcrichton/rust/snapshots, r=luqmana
Merge branch 'master' of github.com:mozilla/rust into ios