Rewind the DocumentLifecycle when dirtying state

Source/core/dom/DocumentLifecycle.cpp

Index: Source/core/dom/DocumentLifecycle.cpp
diff --git a/Source/core/dom/DocumentLifecycle.cpp b/Source/core/dom/DocumentLifecycle.cpp
index e1451fcc6a2c9c830c80487530c316387d7a708e..0e5e715b6f2424cd68cb4505cf77bcc4b726ff4d 100644
--- a/Source/core/dom/DocumentLifecycle.cpp
+++ b/Source/core/dom/DocumentLifecycle.cpp
@@ -74,9 +74,6 @@ DocumentLifecycle::~DocumentLifecycle()
 
 bool DocumentLifecycle::canAdvanceTo(State state) const
 {
-    // This transition is bogus, but we've whitelisted it anyway.
-    if (s_deprecatedTransitionStack && m_state == s_deprecatedTransitionStack->from() && state == s_deprecatedTransitionStack->to())
-        return true;
     if (state > m_state)
         return true;
     if (m_state == Disposed) {
@@ -85,8 +82,6 @@ bool DocumentLifecycle::canAdvanceTo(State state) const
         return state == Disposed;
     }
     if (m_state == StyleClean) {
-        if (state == StyleRecalcPending)
-            return true;
         // We can synchronously recalc style.
         if (state == InStyleRecalc)
             return true;
@@ -119,8 +114,6 @@ bool DocumentLifecycle::canAdvanceTo(State state) const
         return false;
     }
     if (m_state == LayoutClean) {
-        if (state == StyleRecalcPending)
-            return true;
         // We can synchronously recalc style.
         if (state == InStyleRecalc)
             return true;
@@ -138,8 +131,6 @@ bool DocumentLifecycle::canAdvanceTo(State state) const
         return false;
     }
     if (m_state == CompositingClean) {
-        if (state == StyleRecalcPending)
-            return true;
         if (state == InStyleRecalc)
             return true;
         if (state == InPreLayout)
@@ -151,6 +142,14 @@ bool DocumentLifecycle::canAdvanceTo(State state) const
     return false;
 }
 
+bool DocumentLifecycle::canRewindTo(State state) const
+{
+    // This transition is bogus, but we've whitelisted it anyway.
+    if (s_deprecatedTransitionStack && m_state == s_deprecatedTransitionStack->from() && state == s_deprecatedTransitionStack->to())
+        return true;
+    return m_state == StyleClean || m_state == AfterPerformLayout || m_state == LayoutClean || m_state == CompositingClean;
+}
+
 #endif
 
 void DocumentLifecycle::advanceTo(State state)
@@ -159,4 +158,13 @@ void DocumentLifecycle::advanceTo(State state)
     m_state = state;
 }
 
+void DocumentLifecycle::ensureStateAtMost(State state)
+{
+    ASSERT(state == VisualUpdatePending || state == StyleClean || state == LayoutClean);
+    if (m_state <= state)
+        return;
+    ASSERT(canRewindTo(state));
+    m_state = state;
+}
+
 }