Fix: correct framerate for 25Hz IVF file

Remove legacy workaround.
BUG=aomedia:85

Change-Id: I98ab7a3e3e88300586106982dc1fe3a023b361e0

ivfdec.c

diff --git a/ivfdec.c b/ivfdec.c
index 4182e11..93b1f27 100644
--- a/ivfdec.c
+++ b/ivfdec.c
@@ -20,19 +20,8 @@
 static const char *IVF_SIGNATURE = "DKIF";
 
 static void fix_framerate(int *num, int *den) {
-  // Some versions of aomenc used 1/(2*fps) for the timebase, so
-  // we can guess the framerate using only the timebase in this
-  // case. Other files would require reading ahead to guess the
-  // timebase, like we do for webm.
-  if (*den > 0 && *den < 1000000000 && *num > 0 && *num < 1000) {
-    // Correct for the factor of 2 applied to the timebase in the encoder.
-    if (*num & 1)
-      *den *= 2;
-    else
-      *num /= 2;
-  } else {
-    // Don't know FPS for sure, and don't have readahead code
-    // (yet?), so just default to 30fps.
+  if (*den <= 0 || *den >= 1000000000 || *num <= 0 || *num >= 1000) {
+    // framerate seems to be invalid, just default to 30fps.
     *num = 30;
     *den = 1;
   }