Fix SourceBuffer.timestampOffset setter behavior for invalid values.

Source/modules/mediasource/SourceBuffer.cpp

Index: Source/modules/mediasource/SourceBuffer.cpp
diff --git a/Source/modules/mediasource/SourceBuffer.cpp b/Source/modules/mediasource/SourceBuffer.cpp
index c0d64a19a4fbc826d2c88a0836020271ba4cc64e..2730be3020d7163cb7ddba6e275189780b167965 100644
--- a/Source/modules/mediasource/SourceBuffer.cpp
+++ b/Source/modules/mediasource/SourceBuffer.cpp
@@ -175,6 +175,14 @@ double SourceBuffer::timestampOffset() const
 
 void SourceBuffer::setTimestampOffset(double offset, ExceptionState& exceptionState)
 {
+    // Enforce throwing an exception on restricted double values.
+    if (std::isnan(offset)

[wolenetz, 2014/03/17 20:11:39]

nit: use !std::isfinite(offset)?

[acolwell GONE FROM CHROMIUM, 2014/03/17 20:28:27]

Done.

+        || offset == std::numeric_limits<double>::infinity()
+        || offset == -std::numeric_limits<double>::infinity()) {
+        exceptionState.throwDOMException(TypeMismatchError, ExceptionMessages::notAFiniteNumber(offset));
+        return;
+    }
+
     // Section 3.1 timestampOffset attribute setter steps.
     // 1. Let new timestamp offset equal the new value being assigned to this attribute.
     // 2. If this object has been removed from the sourceBuffers attribute of the parent media source, then throw an