[css-sizing] Ensure positive available size on replaced elements

third_party/WebKit/Source/platform/Length.h

Index: third_party/WebKit/Source/platform/Length.h
diff --git a/third_party/WebKit/Source/platform/Length.h b/third_party/WebKit/Source/platform/Length.h
index e170642da04838abe7a9af02eb25194738d2693b..2928356f840cb5e15efcdbed91539883ee8c4112 100644
--- a/third_party/WebKit/Source/platform/Length.h
+++ b/third_party/WebKit/Source/platform/Length.h
@@ -249,6 +249,13 @@ class PLATFORM_EXPORT Length {
   bool isPercentOrCalc() const {
     return type() == Percent || type() == Calculated;
   }
+  // This group of lengths require layout because they need the containing
+  // block's available size. There might be other reasons that could imply
+  // a Length requiring a layout, but in that case we should re-define the
+  // function that groups all these Lengths.
+  bool isLayoutDependent() const {
+    return isPercentOrCalc() || isFillAvailable() || isFitContent();
+  }
 
   Length blend(const Length& from, double progress, ValueRange range) const {
     ASSERT(isSpecified() && from.isSpecified());