~: Allows go run accept .gg file

~: Allows struct-init syntax into for_loop condition

~: Last item without comma is allowed

[release-branch.go1.9] go1.9.1

Change-Id: I711b38738a7f6fade42a2821908234940f3cf280
Reviewed-on: https://go-review.googlesource.com/68233
Reviewed-by: Russ Cox <[email protected]>

[release-branch.go1.8] go1.8.4

Change-Id: Iae6c1ccd1e42656fa5a57d6367e43085143cd590
Reviewed-on: https://go-review.googlesource.com/68234
Reviewed-by: Russ Cox <[email protected]>

[release-branch.go1.9] go1.9

Change-Id: I0899ec0150f2a051b7572879b446a8548f742ae0
Reviewed-on: https://go-review.googlesource.com/58731
Run-TryBot: Chris Broadfoot <[email protected]>
TryBot-Result: Gobot Gobot <[email protected]>
Reviewed-by: Brad Fitzpatrick <[email protected]>
Reviewed-by: Ian Lance Taylor <[email protected]>

[release-branch.go1.9] go1.9rc2

Change-Id: If95cec0ec7e32cdb450818c4c55e2d03b847ab65
Reviewed-on: https://go-review.googlesource.com/53630
Reviewed-by: Austin Clements <[email protected]>

[release-branch.go1.9] go1.9rc1

Change-Id: I6251fc128990f9494a0b037cabb24ada5eabb6b5
Reviewed-on: https://go-review.googlesource.com/50951
Run-TryBot: Chris Broadfoot <[email protected]>
Reviewed-by: Brad Fitzpatrick <[email protected]>
Reviewed-by: Chris Broadfoot <[email protected]>

cmd/go: add more info in t.Fatal message

Updates golang#20284

Change-Id: I4d55d6adec4e8efb54285ca27bb4fa39c76582c3
Reviewed-on: https://go-review.googlesource.com/46719
Reviewed-by: Chris Broadfoot <[email protected]>

cmd/go: disable tool version check during bootstrap

The check that the go tool version matched the go compiler version was
too aggressive and didn't cover the bootstrapping case with make.bash.

We never noticed because we never had a VERSION file in place.

Repro:

$ echo "go1.9beta1" > $GOROOT/VERSION
$ cd $GOROOT/src
$ ./make.bash

No test, because x/build/cmd/release catches it.

Updates golang#19064
Fixes golang#20674

Change-Id: Ibdd7a92377f4cc77d71ed548f02d48bde6550f67
Reviewed-on: https://go-review.googlesource.com/45778
Reviewed-by: Chris Broadfoot <[email protected]>