message: vertexcodec: Update assertion comments
  This changes comments so that they can be recognized by coverage reporting.
diff: @@ -309,7 +309,7 @@ static const unsigned char* decodeBytesGroup(const unsigned char* data, unsigned
  memcpy(buffer, data, kByteGroupSize);
  return data + kByteGroupSize;
  default:
  - assert(!"Unexpected bit length"); // This can never happen since bitslog2 is a 2-bit value
  + assert(!"Unexpected bit length"); // unreachable since bitslog2 is a 2-bit value
  return data;
  }
  @@ -521,7 +521,7 @@ static const unsigned char* decodeBytesGroupSimd(const unsigned char* data, unsi
  }
  default:
  - assert(!"Unexpected bit length"); // This can never happen since bitslog2 is a 2-bit value
  + assert(!"Unexpected bit length"); // unreachable since bitslog2 is a 2-bit value
  return data;
  }
  }
  @@ -649,7 +649,7 @@ static const unsigned char* decodeBytesGroupSimd(const unsigned char* data, unsi
  }
  default:
  - assert(!"Unexpected bit length"); // This can never happen since bitslog2 is a 2-bit value
  + assert(!"Unexpected bit length"); // unreachable since bitslog2 is a 2-bit value
  return data;
  }
  }
  