Gets a 64-bit floating point number at the current {@code readerIndex}
in Little Endian Byte Order and increases the {@code readerIndex}
by {@code 8} in this buffer.
@throws IndexOutOfBoundsException
if {@code this.readableBytes} is less than {@code 8}
Gets a 64-bit floating point number at the current {@code readerIndex} in Little Endian Byte Order and increases the {@code readerIndex} by {@code 8} in this buffer.
@throws IndexOutOfBoundsException if {@code this.readableBytes} is less than {@code 8}