feat: update one-var for class static blocks (#15317)

Fixes false positives of the `one-var` rule with option `"always"` where the rule suggests combining declarations from a class static block with declarations from the upper scope.

Also enables autofixing declarations at the top level of class static blocks with option `"never"`.

Refs #15016

Author: mdjermanovic

docs/rules/one-var.md

@@ -66,7 +66,6 @@ Examples of **incorrect** code for this rule with the default `"always"` option:
 
 ```js
 /*eslint one-var: ["error", "always"]*/
-/*eslint-env es6*/
 
 function foo() {
     var bar;
@@ -89,13 +88,31 @@ function foo() {
         var qux = true;
     }
 }
+
+class C {
+    static {
+        var foo;
+        var bar;
+    }
+
+    static {
+        var foo;
+        if (bar) {
+            var baz = true;
+        }
+    }
+
+    static {
+        let foo;
+        let bar;
+    }
+}
 ```
 
 Examples of **correct** code for this rule with the default `"always"` option:
 
 ```js
 /*eslint one-var: ["error", "always"]*/
-/*eslint-env es6*/
 
 function foo() {
     var bar,
@@ -127,6 +144,30 @@ function foo(){
         let qux;
     }
 }
+
+class C {
+    static {
+        var foo, bar;
+    }
+
+    static {
+        var foo, baz;
+        if (bar) {
+            baz = true;
+        }
+    }
+
+    static {
+        let foo, bar;
+    }
+
+    static {
+        let foo;
+        if (bar) {
+            let baz;
+        }
+    }
+}
 ```
 
 ### never
@@ -135,7 +176,6 @@ Examples of **incorrect** code for this rule with the `"never"` option:
 
 ```js
 /*eslint one-var: ["error", "never"]*/
-/*eslint-env es6*/
 
 function foo() {
     var bar,
@@ -157,13 +197,19 @@ function foo(){
     let bar = true,
         baz = false;
 }
+
+class C {
+    static {
+        var foo, bar;
+        let baz, qux;
+    }
+}
 ```
 
 Examples of **correct** code for this rule with the `"never"` option:
 
 ```js
 /*eslint one-var: ["error", "never"]*/
-/*eslint-env es6*/
 
 function foo() {
     var bar;
@@ -185,6 +231,15 @@ function foo() {
         let qux = true;
     }
 }
+
+class C {
+    static {
+        var foo;
+        var bar;
+        let baz;
+        let qux;
+    }
+}
 ```
 
 ### consecutive
@@ -193,7 +248,6 @@ Examples of **incorrect** code for this rule with the `"consecutive"` option:
 
 ```js
 /*eslint one-var: ["error", "consecutive"]*/
-/*eslint-env es6*/
 
 function foo() {
     var bar;
@@ -209,14 +263,21 @@ function foo(){
     var qux = 3;
     var quux;
 }
+
+class C {
+    static {
+        var foo;
+        var bar;
+        let baz;
+        let qux;
+    }
+}
 ```
 
 Examples of **correct** code for this rule with the `"consecutive"` option:
 
 ```js
 /*eslint one-var: ["error", "consecutive"]*/
-/*eslint-env es6*/
-
 
 function foo() {
     var bar,
@@ -232,6 +293,16 @@ function foo(){
     var qux = 3,
         quux;
 }
+
+class C {
+    static {
+        var foo, bar;
+        let baz, qux;
+        doSomething();
+        let quux;
+        var quuux;
+    }
+}
 ```
 
 ### var, let, and const

lib/rules/one-var.js

@@ -541,6 +541,8 @@ module.exports = {
             FunctionDeclaration: startFunction,
             FunctionExpression: startFunction,
             ArrowFunctionExpression: startFunction,
+            StaticBlock: startFunction, // StaticBlock creates a new scope for `var` variables
+
             BlockStatement: startBlock,
             ForStatement: startBlock,
             ForInStatement: startBlock,
@@ -552,10 +554,12 @@ module.exports = {
             "ForInStatement:exit": endBlock,
             "SwitchStatement:exit": endBlock,
             "BlockStatement:exit": endBlock,
+
             "Program:exit": endFunction,
             "FunctionDeclaration:exit": endFunction,
             "FunctionExpression:exit": endFunction,
-            "ArrowFunctionExpression:exit": endFunction
+            "ArrowFunctionExpression:exit": endFunction,
+            "StaticBlock:exit": endFunction
         };
 
     }