IntersectionObserver: remove gc-timing-revealing execeptions.

third_party/WebKit/Source/core/dom/IntersectionObserver.cpp

Index: third_party/WebKit/Source/core/dom/IntersectionObserver.cpp
diff --git a/third_party/WebKit/Source/core/dom/IntersectionObserver.cpp b/third_party/WebKit/Source/core/dom/IntersectionObserver.cpp
index 9cf2e7ded17bcf02d39004910123108e35aabd6b..408fc2c21c8c4fa315a352cb12f394a5fbf0b496 100644
--- a/third_party/WebKit/Source/core/dom/IntersectionObserver.cpp
+++ b/third_party/WebKit/Source/core/dom/IntersectionObserver.cpp
@@ -230,12 +230,8 @@ Document& IntersectionObserver::trackingDocument() const {
 
 void IntersectionObserver::observe(Element* target,
                                    ExceptionState& exceptionState) {
-  if (!rootIsValid()) {
-    exceptionState.throwDOMException(
-        InvalidStateError,
-        "observe() called on an IntersectionObserver with an invalid root.");
+  if (!rootIsValid())
     return;
-  }
 
   if (!target || root() == target)
     return;
@@ -287,19 +283,14 @@ void IntersectionObserver::observe(Element* target,
 
 void IntersectionObserver::unobserve(Element* target,
                                      ExceptionState& exceptionState) {
-  if (!rootIsValid()) {
-    exceptionState.throwDOMException(
-        InvalidStateError,
-        "unobserve() called on an IntersectionObserver with an invalid root.");
-    return;
-  }
-
   if (!target || !target->intersectionObserverData())
     return;
 
   if (IntersectionObservation* observation =
-          target->intersectionObserverData()->getObservationFor(*this))
+          target->intersectionObserverData()->getObservationFor(*this)) {
     observation->disconnect();
+    m_observations.remove(observation);
+  }
 }
 
 void IntersectionObserver::computeIntersectionObservations() {
@@ -318,23 +309,11 @@ void IntersectionObserver::computeIntersectionObservations() {
 }
 
 void IntersectionObserver::disconnect(ExceptionState& exceptionState) {
-  if (!rootIsValid()) {
-    exceptionState.throwDOMException(
-        InvalidStateError,
-        "disconnect() called on an IntersectionObserver with an invalid root.");
-    return;
-  }
-
   for (auto& observation : m_observations)
-    observation->clearRootAndRemoveFromTarget();
+    observation->disconnect();
   m_observations.clear();
 }
 
-void IntersectionObserver::removeObservation(
-    IntersectionObservation& observation) {
-  m_observations.remove(&observation);
-}
-
 void IntersectionObserver::setInitialState(InitialState initialState) {
   DCHECK(m_observations.isEmpty());
   m_initialState = initialState;
@@ -343,16 +322,7 @@ void IntersectionObserver::setInitialState(InitialState initialState) {
 HeapVector<Member<IntersectionObserverEntry>> IntersectionObserver::takeRecords(
     ExceptionState& exceptionState) {
   HeapVector<Member<IntersectionObserverEntry>> entries;
-
-  if (!rootIsValid()) {
-    exceptionState.throwDOMException(InvalidStateError,
-                                     "takeRecords() called on an "
-                                     "IntersectionObserver with an invalid "
-                                     "root.");
-  } else {
-    entries.swap(m_entries);
-  }
-
+  entries.swap(m_entries);
   return entries;
 }