Remove docs discouraging single-line conditionals

Our linting rules currently allow braceless conditionals, and we have
hundreds of instances of it in the codebase. It's fairly clear that this
is acceptable in general to our engineers, so we shouldn't discourage it
in our docs.

doc/development/fe_guide/style/javascript.md

@@ -189,24 +189,6 @@ are loaded dynamically with webpack.
 Do not use `innerHTML`, `append()` or `html()` to set content. It opens up too many
 vulnerabilities.
 
-## Avoid single-line conditional statements
-
-Indentation is important when scanning code as it gives a quick indication of the existence of branches, loops, and return points.
-This can help to quickly understand the control flow.
-
-```javascript
-// bad
-if (isThingNull) return '';
-
-if (isThingNull)
-  return '';
-
-// good
-if (isThingNull) {
-  return '';
-}
-```
-
 ## ESLint
 
 ESLint behavior can be found in our [tooling guide](../tooling.md).