IntersectionObserver: check threshold parameters for NaN.

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 fbe2e1b875941bc5b194d4e415a06a7150da55e0..4f2451092ab7f37c36ab7ba2b6f69e7a370619d4 100644
--- a/third_party/WebKit/Source/core/dom/IntersectionObserver.cpp
+++ b/third_party/WebKit/Source/core/dom/IntersectionObserver.cpp
@@ -112,8 +112,8 @@ void parseThresholds(const DoubleOrDoubleArray& thresholdParameter, Vector<float
     }
 
     for (auto thresholdValue : thresholds) {
-        if (thresholdValue < 0.0 || thresholdValue > 1.0) {
-            exceptionState.throwRangeError("Threshold values must be between 0 and 1");
+        if (std::isnan(thresholdValue) || thresholdValue < 0.0 || thresholdValue > 1.0) {
+            exceptionState.throwRangeError("Threshold values must be numbers between 0 and 1");
             break;
         }
     }