[resize-observer] Removed references & algo to device-pixel-border-box until progress is made on the Github issue

Author: Greg Whitworth

resize-observer-1/Overview.bs

@@ -135,20 +135,14 @@ It is modeled after {{MutationObserver}} and {{IntersectionObserver}}.
 
 <pre class="idl">
     enum ResizeObserverBoxOptions {
-        "border-box", "content-box", "device-pixel-border-box"
+        "border-box", "content-box"
     };
 </pre>
 
 ResizeObserver can observe different kinds of CSS sizes:
 
 * {{border-box}}  : size of <a>box border area</a> as defined in CSS2.
 * {{content-box}} : size of <a>content area</a> as defined in CSS2.
-* {{device-pixel-border-box}} : border-box size in device pixels.
-
-{{device-pixel-border-box}} is slightly different from other sizes.
-It can only be observed for {{HTMLCanvasElement}}.
-It can change even when css has only changed location due to rounding,
-because device-pixel sizes are never fractional.
 
 <pre class="idl">
     dictionary ResizeObserverOptions {
@@ -197,21 +191,11 @@ interface ResizeObserver {
     ::
         Adds target to the list of observed elements.
 
-        1. If |options|.box is "device-pixel-border-box" and |target|'s interface is not
-            {{HTMLCanvasElement}} then raise an error.
-
-            1. Create new {{ErrorEvent}} |error|, with message
-                "Only &lt;canvas&gt; elements can observe 'device-pixel-border-box'."
-
-            2. Report an exception |error|.
-
-            3. Return.
+        1. If |target| is in {{ResizeObserver/observationTargets}} slot, call unobserve(<var>target</var>).
 
-        2. If |target| is in {{ResizeObserver/observationTargets}} slot, call unobserve(<var>target</var>).
+        2. Let |resizeObservation| be new {{ResizeObservation}}(<var>target</var>, <var>options</var>).
 
-        3. Let |resizeObservation| be new {{ResizeObservation}}(<var>target</var>, <var>options</var>).
-
-        4. Add the |resizeObservation| to the <var>observationTargets</var> slot.
+        3. Add the |resizeObservation| to the <var>observationTargets</var> slot.
 
     :  <dfn method for="ResizeObserver">unobserve(target)</dfn>
     ::
@@ -251,7 +235,6 @@ interface ResizeObserverEntry {
     readonly attribute DOMRectReadOnly contentRect;
     readonly attribute ResizeObserverSize borderBoxSize;
     readonly attribute ResizeObserverSize contentSize;
-    readonly attribute ResizeObserverSize devicePixelBorderBoxSize;
 };
 </pre>
 
@@ -271,9 +254,6 @@ interface ResizeObserverEntry {
     : <dfn>contentSize</dfn>
     ::
         {{Element}}'s <a>content rect</a> size when {{ResizeObserverCallback}} is invoked.
-    : <dfn>devicePixelBorderBoxSize</dfn>
-    ::
-        {{Element}}'s <a>border box</a> size in device pixels when {{ResizeObserverCallback}} is invoked.
 </div>
 
 <div dfn-type="method" dfn-for="ResizeObserverEntry">
@@ -289,18 +269,15 @@ interface ResizeObserverEntry {
         4. Set |this|.{{ResizeObserverEntry/contentSize}} slot to result of <a href="#calculate-box-size">
             computing size given |target| and specificSize of "content-box"</a>.
 
-        5. Set |this|.{{ResizeObserverEntry/devicePixelBorderBoxSize}} slot to result of <a href="#calculate-box-size">
-            computing size given |target| and specificSize of "device-pixel-border-box"</a>.
+        5. Set |this|.{{ResizeObserverEntry/contentRect}} to logical |this|.{{ResizeObserverEntry/contentSize}}.
 
-        6. Set |this|.{{ResizeObserverEntry/contentRect}} to logical |this|.{{ResizeObserverEntry/contentSize}}.
-
-        7. If |target| is not an SVG element do these steps:
+        6. If |target| is not an SVG element do these steps:
 
             1. Set |this|.|contentRect|.top to |target|.<a>padding top</a>.
 
             2. Set |this|.|contentRect|.left to |target|.<a>padding left</a>.
 
-        8. If |target| is an SVG element do these steps:
+        7. If |target| is an SVG element do these steps:
 
             1. Set |this|.|contentRect|.top and |this|.contentRect.left to 0.
 
@@ -478,9 +455,6 @@ run these steps:
 
             2. Matching size is |entry|.{{ResizeObserverEntry/contentSize}} if |observation|.{{ResizeObservation/observedBox}} is "content-box"
 
-            3. Matching size is |entry|.{{ResizeObserverEntry/devicePixelBorderBoxSize}}
-                if |observation|.{{ResizeObservation/observedBox}} is "device-pixel-border-box"
-
         4. Set |targetDepth| to the result of <a>calculate depth for node</a> for |observation|.{{ResizeObservation/target}}.
 
         5. Set |shallowestTargetDepth| to |targetDepth| if |targetDepth| < |shallowestTargetDepth|