Fix bug in StringBuffer tests that depends upon the default size of a stringbuffer (it fails if there are less than 7 characters available and doesn't explicitly reserve space).
Fix bug in StringBuffer tests that depends upon the default size of a stringbuffer (it fails if there are less than 7 characters available and doesn't explicitly reserve space).

kevinhendricks/gumbo-parser,lvchao0428/gumbo-parser,f123h456/gumbo-parser,lvchao0428/gumbo-parser,luoxn28/gumbo-parser,urandu/gumbo-parser,mcanthony/gumbo-parser,urandu/gumbo-parser,lvchao0428/gumbo-parser,abc00/gumbo-parser,google/gumbo-parser,mcanthony/gumbo-parser,aleksandaratanasov/gumbo-parser,abc00/gumbo-parser,aleksandaratanasov/gumbo-parser,luoxn28/gumbo-parser,mcanthony/gumbo-parser,f123h456/gumbo-parser,lvchao0428/gumbo-parser,abc00/gumbo-parser,kevinhendricks/gumbo-parser,f123h456/gumbo-parser,google/gumbo-parser,abc00/gumbo-parser,urandu/gumbo-parser,aleksandaratanasov/gumbo-parser,google/gumbo-parser,google/gumbo-parser,mcanthony/gumbo-parser,kevinhendricks/gumbo-parser,aleksandaratanasov/gumbo-parser,mcanthony/gumbo-parser,f123h456/gumbo-parser,kevinhendricks/gumbo-parser,urandu/gumbo-parser,lvchao0428/gumbo-parser,abc00/gumbo-parser,kevinhendricks/gumbo-parser,f123h456/gumbo-parser,aleksandaratanasov/gumbo-parser,luoxn28/gumbo-parser,luoxn28/gumbo-parser,google/gumbo-parser,urandu/gumbo-parser,luoxn28/gumbo-parser