Add tools script to update homebrew, the MacOS SDK updating solution.

Add tools script to update homebrew, the MacOS SDK updating solution.

BUG=dartbug.com/20210
R=sgjesse@google.com

Committed: https://code.google.com/p/dart/source/detail?r=40801

[Bill Hesse, 2014-09-26 08:42:33]

whesse@google.com changed reviewers:
+ ricow@google.com

[Søren Gjesse, 2014-09-26 08:55:00]

sgjesse@google.com changed reviewers:
+ sgjesse@google.com

[Søren Gjesse, 2014-09-26 08:55:00]

dbc.

https://codereview.chromium.org/608693004/diff/1/tools/apps/update_homebrew/b...
File tools/apps/update_homebrew/bin/update_homebrew.dart (right):

https://codereview.chromium.org/608693004/diff/1/tools/apps/update_homebrew/b...
tools/apps/update_homebrew/bin/update_homebrew.dart:54: Future
modifyHomebrewFormulas(String channel, int revision) {
Wouldn't it be easier to have the full Ruby source code for the formulas in here
instead of modifying what is in the repro? Seems less error-prone.

[Bill Hesse, 2014-09-29 14:18:12]

PTAL.  Updated to write out the data to two data files, rather than modifying
the formula files.

[Søren Gjesse, 2014-09-29 16:22:18]

lgtm

https://codereview.chromium.org/608693004/diff/40001/tools/apps/update_homebr...
File tools/apps/update_homebrew/pubspec.yaml (right):

https://codereview.chromium.org/608693004/diff/40001/tools/apps/update_homebr...
tools/apps/update_homebrew/pubspec.yaml:4: args: "0.12.0+2"
Make it ">=0.12.0+2 <0.13.0"

https://codereview.chromium.org/608693004/diff/40001/tools/apps/update_homebr...
tools/apps/update_homebrew/pubspec.yaml:5: googleapis: "0.2.0"
Make it ">=0.2.0 <0.3.0" (or ">=0.2.1 <0.3.0" - I just released .0.2.1)

https://codereview.chromium.org/608693004/diff/40001/tools/apps/update_homebr...
tools/apps/update_homebrew/pubspec.yaml:6: http: "0.11.1+1"
And ">=0.11.1+1 <0.12.0"

[Bill Hesse, 2014-09-30 09:14:54]

Committed patchset #4 (id:60001) manually as 40801 (presubmit successful).

[ricow1, 2014-09-30 10:37:48]

lgtm