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JavaScript

function findCoords(matrix) {
  for (var row = 0; row < matrix.length; row++) {
    for (var col = 0; col < matrix[row].length; col++) {
      if (matrix[row][col]) {
        return createCoordsObj(row, col, matrix);
      }
    }
  }
  return null;
}

function createCoordsObj(row, col, matrix) {
  return {
    x: col,
    y: row,
    width: find('width', row, col, matrix),
    height: find('height', row, col, matrix)
  };
}

function find(type, row, col, matrix) {
  var res = 0;
  while (matrix[row] && matrix[row][col]) { // will finish when element in matrix is false || undefined
    res += 1;
    col += type === 'width' ? 1 : 0;
    row += type === 'width' ? 0 : 1;
  }
  return res;
}

console.log(findCoords([
  [false, false, false, false, false],
  [false, false, false, false, false],
  [false, false, false, false, false],
  [true, true, false, true, true],
  [true, true, false, true, true]
]));