isExtendedWesternEuropeanChar_(b1, b2) {
    // The bytes take the following form:
    // b1 -> |0|0|0|1|C|0|1|S|
    // b2 -> |0|0|1|CHARACTER|
    return ((b1 & 0xf6) === 0x12) && ((b2 & 0xe0) === 0x20);
  }
Checks if the character is in the Extended Western European char. set.
@param {number} b1 Byte 1.
@param {number} b2 Byte 2.
@return {boolean}
@private