Fix array type in CanvasBBoxTracker comment

Remove the "Float32Array" mention in the comment, given that the
implementation usesa  Float64Array.

Actually using a Float32Array passes all the tests we currently have and
reduces memory usage (by 16 bytes per op), however to be sure that it
does not introduce rounding bugs we'd need to `Math.fround` all
operations we do on the clipBox and pendingBBox. It reduces the
readibilty of the code, but we can revisit if this memory usage becomes
a problem.

src/display/canvas_dependency_tracker.js

@@ -78,9 +78,10 @@ const ensureDebugMetadata = (map, key) =>
 class CanvasBBoxTracker {
   #baseTransformStack = [[1, 0, 0, 1, 0, 0]];
 
+  // minX, minY, maxX, maxY
   #clipBox = [-Infinity, -Infinity, Infinity, Infinity];
 
-  // Float32Array<minX, minY, maxX, maxY>
+  // minX, minY, maxX, maxY
   #pendingBBox = new Float64Array(BBOX_INIT);
 
   _pendingBBoxIdx = -1;