Improve CDATA and comment parse performance

[naitoh]

Why?

Since <a><!a and <a><!a> are malformed node, they do not need to be checked before comments and CDATA.

Benchmark : comment (after_doctype)

$ benchmark-driver benchmark/parse_comment.yaml
Calculating -------------------------------------
                         before       after  before(YJIT)  after(YJIT)
       after_doctype     1.306k      5.586k        1.152k       3.569k i/s -     100.000 times in 0.076563s 0.017903s 0.086822s 0.028020s

Comparison:
                    after_doctype
               after:      5585.7 i/s
         after(YJIT):      3568.9 i/s - 1.57x  slower
              before:      1306.1 i/s - 4.28x  slower
        before(YJIT):      1151.8 i/s - 4.85x  slower

• YJIT=ON : 3.09x faster
• YJIT=OFF : 4.28x faster

Benchmark : CDATA

$ benchmark-driver benchmark/parse_cdata.yaml
Calculating -------------------------------------
                         before       after  before(YJIT)  after(YJIT)
                 dom     1.269k      5.548k        1.053k       3.072k i/s -     100.000 times in 0.078808s 0.018026s 0.094976s 0.032553s
                 sax     1.399k      8.244k        1.220k       4.460k i/s -     100.000 times in 0.071458s 0.012130s 0.081958s 0.022422s
                pull     1.411k      8.319k        1.260k       4.806k i/s -     100.000 times in 0.070883s 0.012021s 0.079335s 0.020809s
              stream     1.420k      8.320k        1.254k       4.728k i/s -     100.000 times in 0.070406s 0.012019s 0.079738s 0.021149s

Comparison:
                              dom
               after:      5547.5 i/s
         after(YJIT):      3071.9 i/s - 1.81x  slower
              before:      1268.9 i/s - 4.37x  slower
        before(YJIT):      1052.9 i/s - 5.27x  slower

                              sax
               after:      8244.0 i/s
         after(YJIT):      4459.9 i/s - 1.85x  slower
              before:      1399.4 i/s - 5.89x  slower
        before(YJIT):      1220.1 i/s - 6.76x  slower

                             pull
               after:      8318.8 i/s
         after(YJIT):      4805.6 i/s - 1.73x  slower
              before:      1410.8 i/s - 5.90x  slower
        before(YJIT):      1260.5 i/s - 6.60x  slower

                           stream
               after:      8320.2 i/s
         after(YJIT):      4728.4 i/s - 1.76x  slower
              before:      1420.3 i/s - 5.86x  slower
        before(YJIT):      1254.1 i/s - 6.63x  slower

• YJIT=ON : 2.91x - 3.80x faster
• YJIT=OFF : 4.37x - 5.90x faster