[WTF] MediaTime: compute flags on multiplication with doubles

https://bugs.webkit.org/show_bug.cgi?id=246746

Reviewed by Yusuke Suzuki.

The current multiplication algorithm in WTF::MediaTime updates the time
value without updating the flags. This becomes a problem if the
multiplication promotes the number to infinity.

This patch fixes this problem and adds a test for it.

* Source/WTF/wtf/MediaTime.cpp:
(WTF::MediaTime::operator* const):
* Tools/TestWebKitAPI/Tests/WTF/MediaTime.cpp:
(TestWebKitAPI::TEST):

Canonical link: https://commits.webkit.org/255767@main

Source/WTF/wtf/MediaTime.cpp

@@ -304,13 +304,10 @@ MediaTime MediaTime::operator*(int32_t rhs) const
         return positiveInfiniteTime();
     }
 
-    MediaTime a = *this;
-
-    if (a.hasDoubleValue()) {
-        a.m_timeValueAsDouble *= rhs;
-        return a;
-    }
+    if (hasDoubleValue())
+        return MediaTime::createWithDouble(m_timeValueAsDouble * rhs);
 
+    MediaTime a = *this;
     while (!safeMultiply(a.m_timeValue, rhs, a.m_timeValue)) {
         if (a.m_timeScale == 1)
             return signum(a.m_timeValue) == signum(rhs) ? positiveInfiniteTime() : negativeInfiniteTime();

Tools/TestWebKitAPI/Tests/WTF/MediaTime.cpp

@@ -247,6 +247,8 @@ TEST(WTF, MediaTime)
     EXPECT_EQ(MediaTime::createWithDouble(numeric_limits<double>::lowest()) + MediaTime::createWithDouble(numeric_limits<double>::lowest()), MediaTime::negativeInfiniteTime());
     EXPECT_EQ(MediaTime::createWithDouble(numeric_limits<double>::lowest()) - MediaTime::createWithDouble(numeric_limits<double>::max()), MediaTime::negativeInfiniteTime());
     EXPECT_EQ(MediaTime::createWithDouble(numeric_limits<double>::max()) - MediaTime::createWithDouble(numeric_limits<double>::lowest()), MediaTime::positiveInfiniteTime());
+    EXPECT_NE(MediaTime::createWithDouble(numeric_limits<double>::max()), MediaTime::positiveInfiniteTime());
+    EXPECT_EQ(MediaTime::createWithDouble(numeric_limits<double>::max()) * 2, MediaTime::positiveInfiniteTime());
 
     // Rounding
     EXPECT_EQ(MediaTime(1, 1).toTimeScale(2).timeValue(), 2);