Have special semicolon rules for method definitions

[resolritter]

Closes https://github.com/tree-sitter/tree-sitter-typescript/issues/140

Why it works is already explained in the comment. I had the idea by looking at the following line:

https://github.com/tree-sitter/tree-sitter-typescript/blob/d08f57f2689f9006c8a362454a6070d578aa8017/common/scanner.h#L118-L119

Given that method definitions are also functions and therefore their definition is similar, I thought it was fine to re-use that token instead of creating a new one.

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Initial measurements of parser.c against d08f57f2689f9006c8a362454a6070d578aa8017

typescript:

-#define STATE_COUNT 5987
-#define LARGE_STATE_COUNT 1269
+#define STATE_COUNT 6031
+#define LARGE_STATE_COUNT 1270

tsx:

-#define STATE_COUNT 6292
-#define LARGE_STATE_COUNT 1270
+#define STATE_COUNT 6336
+#define LARGE_STATE_COUNT 1271

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Checklist:

• [ ] All tests pass in CI.
• [x] There are sufficient tests for the new fix/feature.
• [x] Grammar rules have not been renamed unless absolutely necessary.
• [x] The conflicts section hasn't grown too much.
• [ ] The parser size hasn't grown too much (check the value of STATE_COUNT in src/parser.c).

[maxbrunsfeld]

Thanks!