Floats on an empty line should still get positioned.

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 924b1d52140ee051dd94115e57b832038eeab219..18b73082d16c09c4e3ae804715f25c042536855b 100644
--- a/Source/core/layout/LayoutBlockFlowLine.cpp
+++ b/Source/core/layout/LayoutBlockFlowLine.cpp
@@ -756,22 +756,6 @@ void LayoutBlockFlow::layoutRunsAndFloats(LineLayoutState& layoutState)
         deleteLineRange(layoutState, startLine);
     }
 
-    if (!layoutState.isFullLayout() && lastRootBox() && lastRootBox()->endsWithBreak()) {
-        // If the last line before the start line ends with a line break that clear floats,
-        // adjust the height accordingly.
-        // A line break can be either the first or the last object on a line, depending on its direction.
-        if (InlineBox* lastLeafChild = lastRootBox()->lastLeafChild()) {
-            LayoutObject* lastObject = &lastLeafChild->layoutObject();
-            if (!lastObject->isBR())
-                lastObject = &lastRootBox()->firstLeafChild()->layoutObject();
-            if (lastObject->isBR()) {
-                EClear clear = lastObject->style()->clear();
-                if (clear != CNONE)
-                    clearFloats(clear);
-            }
-        }
-    }
-
     layoutRunsAndFloatsInRange(layoutState, resolver, cleanLineStart, cleanLineBidiStatus);
     linkToEndLineIfNeeded(layoutState);
     markDirtyFloatsForPaintInvalidation(layoutState.floats());
@@ -897,10 +881,9 @@ void LayoutBlockFlow::layoutRunsAndFloatsInRange(LineLayoutState& layoutState,
             for (size_t i = 0; i < lineBreaker.positionedObjects().size(); ++i)
                 setStaticPositions(this, lineBreaker.positionedObjects()[i]);
 
-            if (!layoutState.lineInfo().isEmpty()) {
+            if (!layoutState.lineInfo().isEmpty())
                 layoutState.lineInfo().setFirstLine(false);
-                clearFloats(lineBreaker.clear());
-            }
+            clearFloats(lineBreaker.clear());
 
             if (m_floatingObjects && lastRootBox()) {
                 const FloatingObjectSet& floatingObjectSet = m_floatingObjects->set();
@@ -1636,6 +1619,7 @@ RootInlineBox* LayoutBlockFlow::determineStartPosition(LineLayoutState& layoutSt
 {
     RootInlineBox* curr = 0;
     RootInlineBox* last = 0;
+    RootInlineBox* lineBoxWithBreakAndClearance = 0;

[leviw_travelin_and_unemployed, 2015/06/08 20:12:35]

Maybe firstLineBoxWithBreakAndClearance?

 
     // FIXME: This entire float-checking block needs to be broken into a new function.
     bool dirtiedByFloat = false;
@@ -1660,6 +1644,15 @@ RootInlineBox* LayoutBlockFlow::determineStartPosition(LineLayoutState& layoutSt
                 }
             }
 
+            // If the linebox breaks cleanly and with clearance then dirty from at least this point onwards so that we can clear the correct floats without difficulty.
+            if (!lineBoxWithBreakAndClearance && curr->endsWithBreak()) {
+                if (InlineBox* lastLeafChild = curr->lastLeafChild()) {
+                    LayoutObject* lastObject = style()->isLeftToRightDirection() ? &lastLeafChild->layoutObject() : &curr->firstLeafChild()->layoutObject();

[leviw_travelin_and_unemployed, 2015/06/08 20:12:35]

You shouldn't always traverse the first and last leaf child in RTL. How about
this:

InlineBox* lastBox = style()->isLeftToRightDirection() ? &curr->lastLeafChild()
: &curr->firstLeafChild();
if (lastBox && lastBox->layoutObject()->isBr() &&
lastBox()->lastObject()->style()->clear() != CNONE)?

+                    if (lastObject->isBR() && lastObject->style()->clear() != CNONE)

[leviw_travelin_and_unemployed, 2015/06/02 22:10:44]

This seems similar to what
https://blink.lc/blink/commit/?id=712375bd4009d756b411cb80164fa1ed04ee219a was
going for?

+                        lineBoxWithBreakAndClearance = curr;
+                }
+            }
+
             // If a new float has been inserted before this line or before its last known float, just do a full layout.
             bool encounteredNewFloat = false;
             checkFloatsInCleanLine(curr, layoutState.floats(), floatIndex, encounteredNewFloat, dirtiedByFloat);
@@ -1692,6 +1685,8 @@ RootInlineBox* LayoutBlockFlow::determineStartPosition(LineLayoutState& layoutSt
         }
         ASSERT(!firstLineBox() && !lastLineBox());
     } else {
+        if (lineBoxWithBreakAndClearance)
+            curr = lineBoxWithBreakAndClearance;
         if (curr) {
             // We have a dirty line.
             if (RootInlineBox* prevRootBox = curr->prevRootBox()) {