Merge pull request #78 from rakuco/use-webidl-getter-convention

editorial: Use Web IDL's definition conventions for getters.

Author: anssiko

index.bs

@@ -237,9 +237,11 @@ To construct an {{AmbientLightSensor}} object the user agent must invoke the
 
 ### The illuminance attribute ### {#ambient-light-sensor-reading-attribute}
 
-The <a attribute for="AmbientLightSensor">illuminance</a> attribute of the {{AmbientLightSensor}}
-interface represents the [=current light level=] and returns the result of invoking
-[=get value from latest reading=] with `this` and "illuminance" as arguments.
+The {{AmbientLightSensor/illuminance}} getter steps are:
+
+1. Let |illuminance| be the result of invoking [=get value from latest
+   reading=] with [=this=] and "illuminance" as arguments.
+1. Return |illuminance|.
 
 Abstract Operations {#abstract-operations}
 ===================