Merge pull request #5013 from duykhoa/maintenance/contributing-format

Remove trailing spaces and extra lines in CONTRIBUTING.md

CONTRIBUTING.md

@@ -42,7 +42,7 @@ If you find an issue, please do file it on the repository. The [Polymer/polymer
 
 For issues with elements the team maintains, please file directly on the element's repository. If you're not sure if a bug stems from the element or the library, air toward filing it on the element and we'll move the issue if necessary.
 
-Please file issues using the issue template provided, filling out as many fields as possible.  We love examples for addressing issues - issues with a Plunkr, jsFiddle, or jsBin will be much easier for us to work on quickly. You can start with [this jsbin](http://jsbin.com/luhaxab/edit) which sets up the basics to demonstrate a Polymer element.
+Please file issues using the issue template provided, filling out as many fields as possible. We love examples for addressing issues - issues with a Plunkr, jsFiddle, or jsBin will be much easier for us to work on quickly. You can start with [this jsbin](http://jsbin.com/luhaxab/edit) which sets up the basics to demonstrate a Polymer element.
 
 Occasionally we'll close issues if they appear stale or are too vague - please don't take this personally! Please feel free to re-open issues we've closed if there's something we've missed and they still need to be addressed.
 
@@ -90,15 +90,15 @@ To run the Polymer library unit tests:
 
 2.  Install the dependencies:
 
-        npm install && bower install
+		npm install && bower install
 
 3.  Run the tests:
 
-        npm test
+		npm test
 
     Or if you have `web-component-tester` installed locally:
 
-        wct
+		wct
 
 To run individual test suites:
 
@@ -110,45 +110,42 @@ Or:
 
 For example:
 
-    npm test test/unit/template.html
+	npm test test/unit/template.html
 
 You can also run tests in the browser:
 
-    polyserve
+	polyserve
 
 Navigate to:
 
 [`http://localhost:8080/components/polymer/test/runner.html`](http://localhost:8080/components/polymer/test/runner.html)
 
 ### Running Polymer element unit tests
 
-To run the element unit tests, you need a global 
-install of `web-component-tester` or `polyserve` (or both). 
+To run the element unit tests, you need a global install of `web-component-tester` or `polyserve` (or both).
 
-1.  Clone the element repo.
+1. Clone the element repo.
 
-2.  Install the dependencies.
+1. Install the dependencies.
 
-        bower install
+       bower install
 
-3.  Run the tests:
+1. Run the tests:
 
-	    wct
+       wct
 
-	Or run the tests in a browser:
+     Or run the tests in a browser:
 
-		polyserve
+       polyserve
 
-	Navigate to:
+     Navigate to:
 
-	<code>http://localhost:8080/components/<var>element-name</var>/test/runner.html</code>
+     <code>http://localhost:8080/components/<var>element-name</var>/test/runner.html</code>
 
 ### Configuring `web-component-tester`
 
 By default, `web-component-tester` runs tests on all installed browsers. You can configure it
 to run tests on a subset of available browsers, or to run tests remotely using Sauce Labs.
 
-See the [`web-component-tester` README](https://github.com/Polymer/web-component-tester) for 
-information on configuring the tool. 
-
-
+See the [`web-component-tester` README](https://github.com/Polymer/web-component-tester) for
+information on configuring the tool.