Better isPageLogicalHeightKnown() implementation.

third_party/WebKit/Source/core/layout/LayoutBox.cpp

Index: third_party/WebKit/Source/core/layout/LayoutBox.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutBox.cpp b/third_party/WebKit/Source/core/layout/LayoutBox.cpp
index fc48cab3e05c766569f25454af712a7460b27e11..4c9d0e1b733ae399b689711f6c24bbad17259996 100644
--- a/third_party/WebKit/Source/core/layout/LayoutBox.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutBox.cpp
@@ -5516,6 +5516,12 @@ LayoutUnit LayoutBox::pageLogicalHeightForOffset(LayoutUnit offset) const {
       offset + offsetFromLogicalTopOfFirstPage());
 }
 
+bool LayoutBox::isPageLogicalHeightKnown() const {
+  if (const LayoutFlowThread* flowThread = flowThreadContainingBlock())
+    return flowThread->isPageLogicalHeightKnown();
+  return view()->pageLogicalHeight();
+}
+
 LayoutUnit LayoutBox::pageRemainingLogicalHeightForOffset(
     LayoutUnit offset,
     PageBoundaryRule pageBoundaryRule) const {