Merge branch 'scroll-code-blocks' into 'master'

Wrap single lines of code; horizontally scroll multi-line code blocks

## What does this MR do?
Original problem: code blocks were wrapping in issue body

* Multi-line code blocks (```) should scroll horizontally
* Single lines of code (`) should wrap

## Why was this MR needed?
Inconsistent scrolling vs wrapping behavior

## What are the relevant issue numbers?
Closes #19619 

## Screenshots (if relevant)
![Screen_Shot_2016-08-04_at_2.32.30_PM](/uploads/a4abcc81b57ffaa8dc8ce2b70a24bc21/Screen_Shot_2016-08-04_at_2.32.30_PM.png)


See merge request !5675

CHANGELOG

@@ -129,6 +129,7 @@ v 8.11.0 (unreleased)
   - Sensible state specific default sort order for issues and merge requests !5453 (tomb0y)
   - Fix bug where destroying a namespace would not always destroy projects
   - Fix RequestProfiler::Middleware error when code is reloaded in development
+  - Allow horizontal scrolling of code blocks in issue body
   - Catch what warden might throw when profiling requests to re-throw it
   - Avoid commit lookup on diff_helper passing existing local variable to the helper method
   - Add description to new_issue email and new_merge_request_email in text/plain content type. !5663 (dixpac)

app/assets/stylesheets/framework/typography.scss

@@ -14,12 +14,20 @@
     margin-top: 0;
   }
+  // Single code lines should wrap
   code {
     font-family: $monospace_font;
-    white-space: pre;
+    white-space: pre-wrap;
     word-wrap: normal;
   }
+  // Multi-line code blocks should scroll horizontally
+  pre {
+    code {
+      white-space: pre;
+    }
+  }
+
   kbd {
     display: inline-block;
     padding: 3px 5px;

app/assets/stylesheets/pages/detail_page.scss

@@ -34,11 +34,4 @@
       }
     }
   }
-
-  .wiki {
-    code {
-      white-space: pre-wrap;
-      word-break: keep-all;
-    }
-  }
 }