layout: duplicated flex styles

[TarantinoMariachi]

Bug, enhancement request, or proposal:

CodePen and steps to reproduce the issue:

CodePen Demo which demonstrates the issue:

Detailed Reproduction Steps:

1. Open file: https://ajax.googleapis.com/ajax/libs/angular_material/1.1.12/angular-material.css
2. We can check that there is 2x the same css code for .layout-row > .flex-50 and .layout-column > .flex-50 for all flex-XX

What is the expected behavior?

N/A

What is the current behavior?

N/A

What is the use-case or motivation for changing an existing behavior?

N/A

Which versions of AngularJS, Material, OS, and browsers are affected?

• AngularJS: N/A
• AngularJS Material: At least from 1.1.9 till 1.1.12
• OS: N/A
• Browsers: N/A

Is there anything else we should know? Stack Traces, Screenshots, etc.

N/A

[Splaktar]

Introduced in this PR in 1.1.9: #11247
Related to this PR which reverted most of the previous PR in 1.1.10: #11331

[Splaktar]

PR #11613 fixes this. Thank you for the report!