This commit teaches parser to parse two libSyntax nodes: FunctionCallArgument and
FunctionCallArgumentList. Along with the change, some libSyntax parsing infrastructure changes
as well: (1) parser doesn't directly insert token into the buffer for libSyntax node creation;
instead, when creating a simple libSyntax node like integer literal expression, parser should indicate the location of the last token in the node; (2) implicit libSyntax nodes like empty
statement list must contain a source location indicating where the implicit nodes should appear
(immediately before the token at the given location).
This commit teaches parser to generate code block syntax node. As a support for this,
SyntaxParsingContext can be created by a single syntax kind, indicating the whole context
should be parsed into a node of that given syntax. Another change is to bridge created syntax
node with the given context kind. For instance, if a statement context results into an expression
node, the expression node will be bridged to a statement by wrapping it with a ExpressionStmt
node.
* Re-apply "libSyntax: Ensure round-trip printing when we build syntax tree from parser incrementally. (#12709)"
* Re-apply "libSyntax: Root parsing context should hold a reference to the current token in the parser, NFC."
* Re-apply "libSyntax: avoid copying token text when lexing token syntax nodes, NFC. (#12723)"
* Actually fix the container-overflow issue.
Since all parsing contexts need a reference to the current token of the
parser, we should pass the token reference to the root context. Therefore, the derived
sub-contexts can just copy it while being spawned.
