Update: max-params to only highlight function header (#10815)

Update the max-params rule to only report the location of the method header. Some tools, like Nuclide, will otherwise highlight the entire body of the method, which makes the rule visually noisy in practice.

Test plan:

npm test

lib/rules/max-params.js

@@ -53,7 +53,7 @@ module.exports = {
     },
 
     create(context) {
-
+        const sourceCode = context.getSourceCode();
         const option = context.options[0];
         let numParams = 3;
 
@@ -76,6 +76,7 @@ module.exports = {
         function checkFunction(node) {
             if (node.params.length > numParams) {
                 context.report({
+                    loc: astUtils.getFunctionHeadLoc(node, sourceCode),
                     node,
                     message: "{{name}} has too many parameters ({{count}}). Maximum allowed is {{max}}.",
                     data: {

tests/lib/rules/max-params.js

@@ -86,6 +86,20 @@ ruleTester.run("max-params", rule, {
                 message: "Function 'test' has too many parameters (3). Maximum allowed is 2.",
                 type: "FunctionDeclaration"
             }]
+        },
+
+        // Error location should not cover the entire function; just the name.
+        {
+            code: `function test(a, b, c) {
+              // Just to make it longer
+            }`,
+            options: [{ max: 2 }],
+            errors: [{
+                line: 1,
+                column: 1,
+                endLine: 1,
+                endColumn: 14
+            }]
         }
     ]
 });