fix(makefile) fix double relevance for assignments (#2278)

* fix(makefile) fix double relevance for assignments

Closes #1976.

- Makefile was claiming 2 relevance for every `x =` pattern
- I'm not sure other grammars get points for assignment,
  so 2 seems off to me.
- Cleaning up the grammar and lowering this rule back to
  1 relevance.

CHANGES.md

@@ -7,6 +7,7 @@ New styles:
   none.
 
 Improvements:
+- fix(makefile) fix double relevance for assigns, improves auto-detection (#2278)[Josh Goebel][]
 - enh(xml) support for highlighting entities (#2260) [w3suli][]
 - enh(gml) fix naming of keyword class (consistency fix) (#2254) [Liam Nobel][]
 - enh(javascript): Add support for jsdoc comments (#2245) [Milutin Kristofic][]

src/languages/makefile.js

@@ -45,16 +45,8 @@ function(hljs) {
     ]
   };
   /* Variable assignment */
-  var VAR_ASSIG = {
-    begin: '^' + hljs.UNDERSCORE_IDENT_RE + '\\s*[:+?]?=',
-    illegal: '\\n',
-    returnBegin: true,
-    contains: [
-      {
-        begin: '^' + hljs.UNDERSCORE_IDENT_RE, end: '[:+?]?=',
-        excludeEnd: true,
-      }
-    ]
+  var ASSIGNMENT = {
+    begin: '^' + hljs.UNDERSCORE_IDENT_RE + '\\s*(?=[:+?]?=)'
   };
   /* Meta targets (.PHONY) */
   var META = {
@@ -80,7 +72,7 @@ function(hljs) {
       VARIABLE,
       QUOTE_STRING,
       FUNC,
-      VAR_ASSIG,
+      ASSIGNMENT,
       META,
       TARGET,
     ]