add syntax highlighting for new rust keywords and types (#3677)

runtime/syntax/rust.yaml

@@ -7,7 +7,7 @@ rules:
     # function definition
     - identifier: "fn [a-z0-9_]+"
       # Reserved words
-    - statement: "\\b(abstract|alignof|as|async|await|become|box|break|const|continue|crate|do|dyn|else|enum|extern|false|final|fn|for|if|impl|in|let|loop|macro|match|mod|move|mut|offsetof|override|priv|pub|pure|ref|return|sizeof|static|self|struct|super|true|trait|type|typeof|unsafe|unsized|use|virtual|where|while|yield)\\b"
+    - statement: "\\b(abstract|alignof|as|async|await|become|box|break|const|continue|crate|do|dyn|else|enum|extern|false|final|fn|for|gen|if|impl|in|let|loop|macro|match|mod|move|mut|offsetof|override|priv|pub|pure|ref|return|sizeof|static|self|struct|super|true|trait|type|typeof|try|unsafe|unsized|use|virtual|where|while|yield)\\b"
       # macros
     - special: "[a-z_]+!"
       # Constants
@@ -19,7 +19,7 @@ rules:
       # Traits/Enums/Structs/Types/etc.
     - type: "\\b[A-Z]+[a-zA-Z_0-9]*[a-z]+[a-zA-Z_0-9]*\\b"
       # Builtin types that start with lowercase.
-    - type: "\\b(bool|str|isize|usize|((i|u)(8|16|32|64))|f32|f64)\\b"
+    - type: "\\b(bool|str|char|((i|u)(8|16|32|64|128|size))|f(16|32|64|128))\\b"
 
     - constant.string:
         start: "[bc]?\""