Revert "Remove obsolete float-management code from line layout"

Source/core/layout/LayoutBlockFlowLine.cpp

Index: Source/core/layout/LayoutBlockFlowLine.cpp
diff --git a/Source/core/layout/LayoutBlockFlowLine.cpp b/Source/core/layout/LayoutBlockFlowLine.cpp
index 73cb7b05fddff414d2de4d325ebb92b8744618a0..f37a019d3e6ede2b2a216174bcfdda5fcd56d09b 100644
--- a/Source/core/layout/LayoutBlockFlowLine.cpp
+++ b/Source/core/layout/LayoutBlockFlowLine.cpp
@@ -36,6 +36,7 @@
 #include "core/layout/line/LayoutTextInfo.h"
 #include "core/layout/line/LineLayoutState.h"
 #include "core/layout/line/LineWidth.h"
+#include "core/layout/line/TrailingFloatsRootInlineBox.h"
 #include "core/layout/line/WordMeasurement.h"
 #include "core/layout/svg/line/SVGRootInlineBox.h"
 #include "platform/fonts/Character.h"
@@ -769,6 +770,7 @@ void LayoutBlockFlow::layoutRunsAndFloatsInRange(LineLayoutState& layoutState,
             // Once BidiRunList is separated from BidiResolver this will not be needed.
             resolver.runs().deleteRuns();
             resolver.markCurrentRunEmpty(); // FIXME: This can probably be replaced by an ASSERT (or just removed).
+            layoutState.setCheckForFloatsFromLastLine(true);
             resolver.setPosition(InlineIterator(resolver.position().root(), 0, 0), 0);
             break;
         }
@@ -965,7 +967,7 @@ void LayoutBlockFlow::linkToEndLineIfNeeded(LineLayoutState& layoutState)
         }
     }
 
-    if (positionNewFloats() && lastRootBox()) {
+    if (m_floatingObjects && (layoutState.checkForFloatsFromLastLine() || positionNewFloats()) && lastRootBox()) {
         // In case we have a float on the last line, it might not be positioned up to now.
         // This has to be done before adding in the bottom border/padding, or the float will
         // include the padding incorrectly. -dwh
@@ -983,6 +985,22 @@ void LayoutBlockFlow::linkToEndLineIfNeeded(LineLayoutState& layoutState)
         if (it == end)
             return;
 
+        if (layoutState.checkForFloatsFromLastLine()) {
+            LayoutUnit bottomVisualOverflow = lastRootBox()->logicalBottomVisualOverflow();
+            LayoutUnit bottomLayoutOverflow = lastRootBox()->logicalBottomLayoutOverflow();
+            TrailingFloatsRootInlineBox* trailingFloatsLineBox = new TrailingFloatsRootInlineBox(*this);
+            m_lineBoxes.appendLineBox(trailingFloatsLineBox);
+            trailingFloatsLineBox->setConstructed();
+            GlyphOverflowAndFallbackFontsMap textBoxDataMap;
+            VerticalPositionCache verticalPositionCache;
+            LayoutUnit blockLogicalHeight = logicalHeight();
+            trailingFloatsLineBox->alignBoxesInBlockDirection(blockLogicalHeight, textBoxDataMap, verticalPositionCache);
+            trailingFloatsLineBox->setLineTopBottomPositions(blockLogicalHeight, blockLogicalHeight, blockLogicalHeight, blockLogicalHeight);
+            LayoutRect logicalLayoutOverflow(0, blockLogicalHeight, 1, bottomLayoutOverflow - blockLogicalHeight);
+            LayoutRect logicalVisualOverflow(0, blockLogicalHeight, 1, bottomVisualOverflow - blockLogicalHeight);
+            trailingFloatsLineBox->setOverflowFromLogicalRects(logicalLayoutOverflow, logicalVisualOverflow, trailingFloatsLineBox->lineTop(), trailingFloatsLineBox->lineBottom());
+        }
+
         for (; it != end; ++it)
             appendFloatingObjectToLastLine(it->get());
     }