Remove the layout.reflow.async.duringDocLoad pref -- setting it to false just

makes us buggy.  Bug 334543, r+sr=dbaron

layout/base/nsPresShell.cpp

@@ -406,10 +406,6 @@ protected:
 #define NS_MAX_REFLOW_TIME    1000000
 static PRInt32 gMaxRCProcessingTime = -1;
 
-// Set to true to enable async reflow during document load.
-// This flag is initialized from the layout.reflow.async.duringDocLoad pref.
-static PRBool gAsyncReflowDuringDocLoad = PR_FALSE;
-
 // Largest chunk size we recycle
 static const size_t gMaxRecycledSize = 400;
 
@@ -1780,10 +1776,6 @@ PresShell::Init(nsIDocument* aDocument,
     gMaxRCProcessingTime =
       nsContentUtils::GetIntPref("layout.reflow.timeslice",
                                  NS_MAX_REFLOW_TIME);
-
-    gAsyncReflowDuringDocLoad =
-      nsContentUtils::GetBoolPref("layout.reflow.async.duringDocLoad",
-                                  PR_TRUE);
   }
 
   {
@@ -3668,13 +3660,12 @@ PresShell::AppendReflowCommand(nsIFrame*    aTargetFrame,
     delete command;
   }
 
-  // For async reflow during doc load, post a reflow event if we are not batching reflow commands.
-  // For sync reflow during doc load, post a reflow event if we are not batching reflow commands
-  // and the document is not loading.
-  if ((gAsyncReflowDuringDocLoad && !mBatchReflows) ||
-      (!gAsyncReflowDuringDocLoad && !mBatchReflows && !mDocumentLoading)) {
+  // Post a reflow event if we are not batching reflow commands.
+  if (!mBatchReflows) {
     // If we're in the middle of a drag, process it right away (needed for mac,
     // might as well do it on all platforms just to keep the code paths the same).
+    // XXXbz but how does this actually "process it right away"?
+    // Isn't this more like "never process it"?
     if ( !IsDragInProgress() )
       PostReflowEvent();
   }
@@ -6460,11 +6451,7 @@ PresShell::DidCauseReflow()
   if (--mChangeNestCount == 0) {
     // We may have had more reflow commands appended to the queue during
     // our reflow.  Make sure these get processed at some point.
-    if (!gAsyncReflowDuringDocLoad && mDocumentLoading) {
-      FlushPendingNotifications(Flush_Layout);
-    } else {
-      PostReflowEvent();
-    }
+    PostReflowEvent();
   }
 
   return NS_OK;
@@ -6649,34 +6636,32 @@ nsresult
 PresShell::ReflowCommandAdded(nsHTMLReflowCommand* aRC)
 {
 
-  if (gAsyncReflowDuringDocLoad) {
-    NS_PRECONDITION(mRCCreatedDuringLoad >= 0, "PresShell's reflow command queue is in a bad state.");
-    if (mDocumentLoading) {
-      aRC->AddFlagBits(NS_RC_CREATED_DURING_DOCUMENT_LOAD);
-      mRCCreatedDuringLoad++;
+  NS_PRECONDITION(mRCCreatedDuringLoad >= 0, "PresShell's reflow command queue is in a bad state.");
+  if (mDocumentLoading) {
+    aRC->AddFlagBits(NS_RC_CREATED_DURING_DOCUMENT_LOAD);
+    mRCCreatedDuringLoad++;
 
 #ifdef PR_LOGGING
-      if (PR_LOG_TEST(gLog, PR_LOG_DEBUG)) {
-        nsIFrame* target;
-        aRC->GetTarget(target);
+    if (PR_LOG_TEST(gLog, PR_LOG_DEBUG)) {
+      nsIFrame* target;
+      aRC->GetTarget(target);
 
-        nsIAtom* type = target->GetType();
-        NS_ASSERTION(type, "frame didn't override GetType()");
+      nsIAtom* type = target->GetType();
+      NS_ASSERTION(type, "frame didn't override GetType()");
 
-        nsAutoString typeStr(NS_LITERAL_STRING("unknown"));
-        if (type)
-          type->ToString(typeStr);
+      nsAutoString typeStr(NS_LITERAL_STRING("unknown"));
+      if (type)
+        type->ToString(typeStr);
 
-        PR_LOG(gLog, PR_LOG_DEBUG,
-               ("presshell=%p, ReflowCommandAdded(%p) target=%p[%s] mRCCreatedDuringLoad=%d\n",
-                this, aRC, target, NS_ConvertUTF16toUTF8(typeStr).get(), mRCCreatedDuringLoad));
-      }
+      PR_LOG(gLog, PR_LOG_DEBUG,
+             ("presshell=%p, ReflowCommandAdded(%p) target=%p[%s] mRCCreatedDuringLoad=%d\n",
+              this, aRC, target, NS_ConvertUTF16toUTF8(typeStr).get(), mRCCreatedDuringLoad));
+    }
 #endif
 
-      if (!mDocumentOnloadBlocked) {
-        mDocument->BlockOnload();
-        mDocumentOnloadBlocked = PR_TRUE;
-      }
+    if (!mDocumentOnloadBlocked) {
+      mDocument->BlockOnload();
+      mDocumentOnloadBlocked = PR_TRUE;
     }
   }
   return NS_OK;
@@ -6689,15 +6674,13 @@ PresShell::ReflowCommandRemoved(nsHTMLReflowCommand* aRC)
   
   PL_DHashTableOperate(&mReflowCommandTable, aRC, PL_DHASH_REMOVE);
   
-  if (gAsyncReflowDuringDocLoad) {
-    NS_PRECONDITION(mRCCreatedDuringLoad >= 0, "PresShell's reflow command queue is in a bad state.");  
-    if (aRC->GetFlagBits() & NS_RC_CREATED_DURING_DOCUMENT_LOAD) {
-      mRCCreatedDuringLoad--;
+  NS_PRECONDITION(mRCCreatedDuringLoad >= 0, "PresShell's reflow command queue is in a bad state.");  
+  if (aRC->GetFlagBits() & NS_RC_CREATED_DURING_DOCUMENT_LOAD) {
+    mRCCreatedDuringLoad--;
 
-      PR_LOG(gLog, PR_LOG_DEBUG,
-             ("presshell=%p, ReflowCommandRemoved(%p) mRCCreatedDuringLoad=%d\n",
-              this, aRC, mRCCreatedDuringLoad));
-    }
+    PR_LOG(gLog, PR_LOG_DEBUG,
+           ("presshell=%p, ReflowCommandRemoved(%p) mRCCreatedDuringLoad=%d\n",
+            this, aRC, mRCCreatedDuringLoad));
   }
   return NS_OK;
 }