Bug 1877850 Part 1 - Convert callers of ReflowInput physical size accessors to use logical ones. r=dholbert

ReflowInput's computed sizes and border&padding are stored in logical
coordinates, so accessing the physical version is slower [1]. This patch
converts as many callers as possible to use logical coordinates.

This patch doesn't change behavior.

[1] For example, accessing `ComputedWidth()` and `ComputedHeight()` needs two
`IsVertical()` check, but `GetPhysicalSize()` only needs one.

Differential Revision: https://phabricator.services.mozilla.com/D200237

layout/generic/ReflowInput.h

@@ -399,7 +399,7 @@ struct ReflowInput : public SizeComputationInput {
   }
 
   nsSize ComputedPhysicalSize() const {
-    return nsSize(ComputedWidth(), ComputedHeight());
+    return mComputedSize.GetPhysicalSize(mWritingMode);
   }
 
   nsMargin ComputedPhysicalOffsets() const {