Bug 371839. Assertions that scan all continuations should bail out if the continuation chain is too long, so they don't add O(N) to algorithmic complexity. r=bzbarsky

layout/generic/nsSplittableFrame.cpp

@@ -131,20 +131,26 @@ nsIFrame* nsSplittableFrame::GetLastContinuation() const
 #ifdef DEBUG
 PRBool nsSplittableFrame::IsInPrevContinuationChain(nsIFrame* aFrame1, nsIFrame* aFrame2)
 {
-  while (aFrame1) {
+  PRInt32 iterations = 0;
+  while (aFrame1 && iterations < 10) {
+    // Bail out after 10 iterations so we don't bog down debug builds too much
     if (aFrame1 == aFrame2)
       return PR_TRUE;
     aFrame1 = aFrame1->GetPrevContinuation();
+    ++iterations;
   }
   return PR_FALSE;
 }
 
 PRBool nsSplittableFrame::IsInNextContinuationChain(nsIFrame* aFrame1, nsIFrame* aFrame2)
 {
-  while (aFrame1) {
+  PRInt32 iterations = 0;
+  while (aFrame1 && iterations < 10) {
+    // Bail out after 10 iterations so we don't bog down debug builds too much
     if (aFrame1 == aFrame2)
       return PR_TRUE;
     aFrame1 = aFrame1->GetNextContinuation();
+    ++iterations;
   }
   return PR_FALSE;
 }

layout/generic/nsTextFrameThebes.cpp

@@ -5958,10 +5958,19 @@ nsTextFrame::SetLength(PRInt32 aLength)
     f = static_cast<nsTextFrame*>(f->GetNextInFlow());
   }
 #ifdef DEBUG
-  f = static_cast<nsTextFrame*>(this->GetFirstContinuation());
-  while (f) {
+  f = this;
+  PRInt32 iterations = 0;
+  while (f && iterations < 10) {
     f->GetContentLength(); // Assert if negative length
     f = static_cast<nsTextFrame*>(f->GetNextContinuation());
+    ++iterations;
+  }
+  f = this;
+  iterations = 0;
+  while (f && iterations < 10) {
+    f->GetContentLength(); // Assert if negative length
+    f = static_cast<nsTextFrame*>(f->GetPrevContinuation());
+    ++iterations;
   }
 #endif
 }