Bug 1592915 - Fix three warnings in `VideoFrameConverter.h` and `TestVideoTrackEncoder.h`. r=pehrsons

This warns because an expression with a side effect is inside a `static_assert` or
`sizeof`.

Differential Revision: https://phabricator.services.mozilla.com/D51243

--HG--
extra : moz-landing-system : lando

dom/media/VideoFrameConverter.h

@@ -360,7 +360,10 @@ class VideoFrameConverter {
     rtc::scoped_refptr<webrtc::I420Buffer> buffer =
         mBufferPool.CreateBuffer(aFrame.mSize.width, aFrame.mSize.height);
     if (!buffer) {
-      MOZ_DIAGNOSTIC_ASSERT(++mFramesDropped <= 100, "Buffers must be leaking");
+#ifdef MOZ_DIAGNOSTIC_ASSERT_ENABLED
+      ++mFramesDropped;
+#endif
+      MOZ_DIAGNOSTIC_ASSERT(mFramesDropped <= 100, "Buffers must be leaking");
       MOZ_LOG(gVideoFrameConverterLog, LogLevel::Warning,
               ("Creating a buffer failed"));
       return;

dom/media/gtest/TestVideoTrackEncoder.cpp

@@ -331,7 +331,8 @@ TEST(VP8VideoTrackEncoder, TimestampFrameEncode)
   uint64_t totalDuration = 0;
   size_t i = 0;
   for (auto& frame : frames) {
-    EXPECT_EQ(expectedDurations[i++], frame->mDuration);
+    EXPECT_EQ(expectedDurations[i], frame->mDuration);
+    i++;
     totalDuration += frame->mDuration;
   }
   const uint64_t pointThree = (PR_USEC_PER_SEC / 10) * 3;
@@ -380,7 +381,8 @@ TEST(VP8VideoTrackEncoder, DriftingFrameEncode)
   uint64_t totalDuration = 0;
   size_t i = 0;
   for (auto& frame : frames) {
-    EXPECT_EQ(expectedDurations[i++], frame->mDuration);
+    EXPECT_EQ(expectedDurations[i], frame->mDuration);
+    i++;
     totalDuration += frame->mDuration;
   }
   const uint64_t pointSix = (PR_USEC_PER_SEC / 10) * 6;