fix error which calculate child to parent position not include scrollLeft and scrollTop

integration_tests/specs/dom/nodes/element.ts

@@ -43,6 +43,39 @@ describe('DOM Element API', () => {
     expect(div.hasAttribute('foo')).toBeFalse();
   });
 
+  it('should work with scroll', () => {
+    const div = document.createElement('div');
+
+    div.style.width = div.style.height = '200px';
+    div.style.padding = '10px';
+    div.style.margin = '20px';
+    div.style.backgroundColor = 'grey';
+    div.style.overflow = 'scroll';
+    document.body.appendChild(div);
+
+    const scrollDiv = document.createElement('div');
+    scrollDiv.style.width = '100px';
+    scrollDiv.style.height = '1000px';
+    div.appendChild(scrollDiv)
+
+    const childDiv = document.createElement('div');
+    childDiv.style.width = childDiv.style.height = '30px';
+    childDiv.style.marginTop = '150px';
+    childDiv.style.backgroundColor = 'yellow';
+    scrollDiv.appendChild(childDiv);
+
+    expect(JSON.parse(JSON.stringify(childDiv.getBoundingClientRect()))).toEqual({
+      bottom: 210, height: 30, left: 30, right: 60, top: 180, width: 30, x: 30, y: 180
+    } as any);
+
+    div.scrollBy(0, 10);
+
+    expect(JSON.parse(JSON.stringify(childDiv.getBoundingClientRect()))).toEqual({
+      bottom: 200, height: 30, left: 30, right: 60, top: 170, width: 30, x: 30, y: 170
+    } as any);
+
+  });
+
   it('children should only contain elements', () => {
     let container = document.createElement('div');
     let a = document.createElement('div');

webf/lib/src/css/positioned.dart

@@ -35,7 +35,7 @@ Offset _getPlaceholderToParentOffset(RenderPositionPlaceholder? placeholder, Ren
   Offset positionHolderScrollOffset = _getRenderPositionHolderScrollOffset(placeholder, parent) ?? Offset.zero;
   // Offset of positioned element should exclude scroll offset to its containing block.
   Offset toParentOffset = placeholder.getOffsetToAncestor(Offset.zero, parent, excludeScrollOffset: true);
-  Offset placeholderOffset = positionHolderScrollOffset + toParentOffset;
+  Offset placeholderOffset = -positionHolderScrollOffset + toParentOffset;
 
   return placeholderOffset;
 }

webf/lib/src/rendering/box_model.dart

@@ -1059,6 +1059,8 @@ class RenderBoxModel extends RenderBox
     final BoxParentData childParentData = child.parentData! as BoxParentData;
     Offset offset = childParentData.offset;
     if (excludeScrollOffset) {
+      offset += Offset(scrollLeft, scrollTop);
+    } else {
       offset -= Offset(scrollLeft, scrollTop);
     }
     transform.translate(offset.dx, offset.dy);