KT-11612 Highlight named arguments in the editor somehow

#KT-11612 Fixed

idea/idea-analysis/src/org/jetbrains/kotlin/idea/highlighter/KotlinHighlightingColors.java

@@ -87,6 +87,7 @@ public class KotlinHighlightingColors {
     public static final TextAttributesKey LABEL = createTextAttributesKey("KOTLIN_LABEL");
     public static final TextAttributesKey DEBUG_INFO = createTextAttributesKey("KOTLIN_DEBUG_INFO");
     public static final TextAttributesKey RESOLVED_TO_ERROR = createTextAttributesKey("KOTLIN_RESOLVED_TO_ERROR");
+    public static final TextAttributesKey NAMED_ARGUMENT = createTextAttributesKey("KOTLIN_NAMED_ARGUMENT");
 
     private KotlinHighlightingColors() {
     }

idea/idea-analysis/src/org/jetbrains/kotlin/idea/highlighter/SoftKeywordsHighlightingVisitor.kt

@@ -18,10 +18,14 @@ package org.jetbrains.kotlin.idea.highlighter
 
 import com.intellij.lang.annotation.AnnotationHolder
 import com.intellij.openapi.application.ApplicationManager
+import com.intellij.openapi.util.TextRange
 import com.intellij.psi.PsiElement
 import org.jetbrains.kotlin.lexer.KtTokens
 import org.jetbrains.kotlin.psi.KtLambdaExpression
+import org.jetbrains.kotlin.psi.KtValueArgument
 import org.jetbrains.kotlin.psi.KtVisitorVoid
+import org.jetbrains.kotlin.psi.psiUtil.endOffset
+import org.jetbrains.kotlin.psi.psiUtil.startOffset
 
 internal class SoftKeywordsHighlightingVisitor(private val holder: AnnotationHolder) : KtVisitorVoid() {
 
@@ -59,4 +63,12 @@ internal class SoftKeywordsHighlightingVisitor(private val holder: AnnotationHol
             holder.createInfoAnnotation(arrow, null).textAttributes = KotlinHighlightingColors.FUNCTION_LITERAL_BRACES_AND_ARROW
         }
     }
+
+    override fun visitArgument(argument: KtValueArgument) {
+        super.visitArgument(argument)
+
+        val argumentName = argument.getArgumentName() ?: return
+        val eq = argument.equalsToken ?: return
+        holder.createInfoAnnotation(TextRange(argumentName.startOffset, eq.endOffset), null).textAttributes = KotlinHighlightingColors.NAMED_ARGUMENT
+    }
 }

idea/idea-analysis/src/org/jetbrains/kotlin/idea/highlighter/VariablesHighlightingVisitor.java

@@ -51,7 +51,10 @@ class VariablesHighlightingVisitor extends AfterAnalysisHighlightingVisitor {
             }
         }
 
-        highlightVariable(expression, target);
+        if (!(expression.getParent() instanceof KtValueArgumentName)) { // highlighted separately
+            highlightVariable(expression, target);
+        }
+
         super.visitSimpleNameExpression(expression);
     }