Fix sizing of absolutely positioned nodes inside overflow:hidden parent

Summary:
When an absolutely positioned node appeared inside an overflow:hidden
parent, we were limiting its height. This is inconsistent with how
layout behaves on the web.
Closes https://github.com/facebook/css-layout/pull/218

Reviewed By: lucasr

Differential Revision: D3797285

Pulled By: emilsjolander

fbshipit-source-id: 98f98e77aa26edce86b9882c1cac284799b69a27

CSSLayout/CSSLayout.c

@@ -1764,16 +1764,6 @@ static void layoutNodeImpl(const CSSNodeRef node,
           childWidthMeasureMode = CSSMeasureModeAtMost;
         }
 
-        // The W3C spec doesn't say anything about the 'overflow' property,
-        // but all major browsers appear to implement the following logic.
-        if (node->style.overflow == CSSOverflowHidden) {
-          if (isMainAxisRow && CSSValueIsUndefined(childHeight) &&
-              !CSSValueIsUndefined(availableInnerHeight)) {
-            childHeight = availableInnerHeight;
-            childHeightMeasureMode = CSSMeasureModeAtMost;
-          }
-        }
-
         layoutNodeInternal(currentAbsoluteChild,
                            childWidth,
                            childHeight,

java/com/facebook/csslayout/LayoutEngine.java

@@ -1336,15 +1336,6 @@ public class LayoutEngine {
             childWidthMeasureMode = CSSMeasureMode.AT_MOST;
           }
 
-          // The W3C spec doesn't say anything about the 'overflow' property,
-          // but all major browsers appear to implement the following logic.
-          if (node.style.overflow == CSSOverflow.HIDDEN) {
-            if (isMainAxisRow && Float.isNaN(childHeight) && !Float.isNaN(availableInnerHeight)) {
-              childHeight = availableInnerHeight;
-              childHeightMeasureMode = CSSMeasureMode.AT_MOST;
-            }
-          }
-
           layoutNodeInternal(layoutContext, currentAbsoluteChild, childWidth, childHeight, direction, childWidthMeasureMode, childHeightMeasureMode, false, "abs-measure");
           childWidth = currentAbsoluteChild.layout.measuredDimensions[DIMENSION_WIDTH] + (currentAbsoluteChild.style.margin.getWithFallback(leadingSpacing[CSS_FLEX_DIRECTION_ROW], leading[CSS_FLEX_DIRECTION_ROW]) + currentAbsoluteChild.style.margin.getWithFallback(trailingSpacing[CSS_FLEX_DIRECTION_ROW], trailing[CSS_FLEX_DIRECTION_ROW]));
           childHeight = currentAbsoluteChild.layout.measuredDimensions[DIMENSION_HEIGHT] + (currentAbsoluteChild.style.margin.getWithFallback(leadingSpacing[CSS_FLEX_DIRECTION_COLUMN], leading[CSS_FLEX_DIRECTION_COLUMN]) + currentAbsoluteChild.style.margin.getWithFallback(trailingSpacing[CSS_FLEX_DIRECTION_COLUMN], trailing[CSS_FLEX_DIRECTION_COLUMN]));

tests/CSSLayoutAbsolutePositionTest.cpp

@@ -22,6 +22,11 @@
  * <div id="absolute_layout_width_height_left_top_right_bottom" style="width: 100px; height: 100px;">
  * <div style="width:10px; height: 10px; position: absolute; left: 10px; top: 10px; right: 10px; bottom: 10px;"></div>
  * </div>
+ * <div id="do_not_clamp_height_of_absolute_node_to_height_of_its_overflow_hidden_parent" style="height: 50px; width: 50px; overflow: hidden; flex-direction: row;">
+ * <div style="position: absolute; left: 0; top: 0;">
+ * <div style="width: 100px; height: 100px;"></div>
+ * </div>
+ * </div>
  *
  */
 
@@ -129,3 +134,36 @@ TEST(CSSLayoutTest, absolute_layout_width_height_left_top_right_bottom) {
   ASSERT_EQ(10, CSSNodeLayoutGetWidth(root_child0));
   ASSERT_EQ(10, CSSNodeLayoutGetHeight(root_child0));
 }
+
+TEST(CSSLayoutTest, do_not_clamp_height_of_absolute_node_to_height_of_its_overflow_hidden_parent) {
+  const CSSNodeRef root = CSSNodeNew();
+  CSSNodeStyleSetFlexDirection(root, CSSFlexDirectionRow);
+  CSSNodeStyleSetOverflow(root, CSSOverflowHidden);
+  CSSNodeStyleSetWidth(root, 50);
+  CSSNodeStyleSetHeight(root, 50);
+
+  const CSSNodeRef root_child0 = CSSNodeNew();
+  CSSNodeStyleSetPositionType(root_child0, CSSPositionTypeAbsolute);
+  CSSNodeInsertChild(root, root_child0, 0);
+
+  const CSSNodeRef root_child0_child0 = CSSNodeNew();
+  CSSNodeStyleSetWidth(root_child0_child0, 100);
+  CSSNodeStyleSetHeight(root_child0_child0, 100);
+  CSSNodeInsertChild(root_child0, root_child0_child0, 0);
+  CSSNodeCalculateLayout(root, CSSUndefined, CSSUndefined, CSSDirectionLTR);
+
+  ASSERT_EQ(0, CSSNodeLayoutGetLeft(root));
+  ASSERT_EQ(0, CSSNodeLayoutGetTop(root));
+  ASSERT_EQ(50, CSSNodeLayoutGetWidth(root));
+  ASSERT_EQ(50, CSSNodeLayoutGetHeight(root));
+
+  ASSERT_EQ(0, CSSNodeLayoutGetLeft(root_child0));
+  ASSERT_EQ(0, CSSNodeLayoutGetTop(root_child0));
+  ASSERT_EQ(100, CSSNodeLayoutGetWidth(root_child0));
+  ASSERT_EQ(100, CSSNodeLayoutGetHeight(root_child0));
+
+  ASSERT_EQ(0, CSSNodeLayoutGetLeft(root_child0_child0));
+  ASSERT_EQ(0, CSSNodeLayoutGetTop(root_child0_child0));
+  ASSERT_EQ(100, CSSNodeLayoutGetWidth(root_child0_child0));
+  ASSERT_EQ(100, CSSNodeLayoutGetHeight(root_child0_child0));
+}