[css-flex] Implement the space-evenly content-distribution value

third_party/WebKit/LayoutTests/css3/flexbox/flex-justify-content.html

Index: third_party/WebKit/LayoutTests/css3/flexbox/flex-justify-content.html
diff --git a/third_party/WebKit/LayoutTests/css3/flexbox/flex-justify-content.html b/third_party/WebKit/LayoutTests/css3/flexbox/flex-justify-content.html
index 2704a0f5db33a9f2b6c72bdfd260694cdbca0d65..e2d2262d2917e4c54dcd1cb8e0e242c0f95929e5 100644
--- a/third_party/WebKit/LayoutTests/css3/flexbox/flex-justify-content.html
+++ b/third_party/WebKit/LayoutTests/css3/flexbox/flex-justify-content.html
@@ -96,6 +96,31 @@ body {
 <!-- Make sure we don't crash with no children. -->
 <div class="flexbox" style="justify-content: space-around"></div>
 
+<div class="flexbox" style="justify-content: space-evenly">
+  <div data-expected-width="100" data-offset-x="75" style="flex: 1 0 0; max-width: 100px;"></div>
+  <div data-expected-width="100" data-offset-x="250" style="width: 100px;"></div>
+  <div data-expected-width="100" data-offset-x="425" style="width: 100px;"></div>
+</div>
+
+<div class="flexbox" style="justify-content: space-evenly">
+  <div data-expected-width="200" data-offset-x="0" style="flex: 1 100px;"></div>
+  <div data-expected-width="200" data-offset-x="200" style="flex: 1 100px;"></div>
+  <div data-expected-width="200" data-offset-x="400" style="flex: 1 100px;"></div>
+</div>
+
+<!-- If there's only one child, we justify-content: center. -->
+<div class="flexbox" style="justify-content: space-evenly">
+  <div data-expected-width="100" data-offset-x="250" style="flex: 1 0 0; max-width: 100px;"></div>
+</div>
+
+<!-- True centering on overflow. -->
+<div class="flexbox" style="justify-content: space-evenly">
+  <div data-expected-width="800" data-offset-x="-100" style="width: 800px;"></div>
+</div>
+
+<!-- Make sure we don't crash with no children. -->
+<div class="flexbox" style="justify-content: space-evenly"></div>
+
 <!-- margin:auto applies before justify-content. -->
 <div class="flexbox" style="justify-content: flex-end">
   <div data-expected-width="100" data-offset-x="0" style="width: 100px;"></div>