Fix FLV parser to skip metadata we're not interested in

Issue: #2634

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=151816597

library/core/src/main/java/com/google/android/exoplayer2/extractor/flv/ScriptTagPayloadReader.java

@@ -80,8 +80,8 @@ import java.util.Map;
     }
     int type = readAmfType(data);
     if (type != AMF_TYPE_ECMA_ARRAY) {
-      // Should never happen.
-      throw new ParserException();
+      // We're not interested in this metadata.
+      return;
     }
     // Set the duration to the value contained in the metadata, if present.
     Map<String, Object> metadata = readAmfEcmaArray(data);