Drop first pass in narrowByTrees

The two pass approach was originally introduced in
295c981 to lower the priority of
implicit conversions, but just a month later in
6253125 a similar two pass approach was
used to call resolveOverloaded which itself calls narrowByTrees,
rendering the first commit moot.

Therefore, we can just remove this first pass and all associated code
without affecting anything.

Author: smarter

compiler/src/dotty/tools/dotc/typer/Applications.scala

@@ -614,7 +614,6 @@ trait Applications extends Compatibility {
 
   /** The degree to which an argument has to match a formal parameter */
   enum ArgMatch:
-    case SubType       // argument is a relaxed subtype of formal
     case Compatible    // argument is compatible with formal
     case CompatibleCAP // capture-converted argument is compatible with formal
 
@@ -639,17 +638,14 @@ trait Applications extends Compatibility {
           case SAMType(sam) => argtpe <:< sam.toFunctionType(isJava = formal.classSymbol.is(JavaDefined))
           case _ => false
         }
-        if argMatch == ArgMatch.SubType then
-          argtpe relaxed_<:< formal.widenExpr
-        else
-          isCompatible(argtpe, formal)
-          || ctx.mode.is(Mode.ImplicitsEnabled) && SAMargOK
-          || argMatch == ArgMatch.CompatibleCAP
-              && {
-                val argtpe1 = argtpe.widen
-                val captured = captureWildcards(argtpe1)
-                (captured ne argtpe1) && isCompatible(captured, formal.widenExpr)
-              }
+        isCompatible(argtpe, formal)
+        || ctx.mode.is(Mode.ImplicitsEnabled) && SAMargOK
+        || argMatch == ArgMatch.CompatibleCAP
+            && {
+              val argtpe1 = argtpe.widen
+              val captured = captureWildcards(argtpe1)
+              (captured ne argtpe1) && isCompatible(captured, formal.widenExpr)
+            }
 
     /** The type of the given argument */
     protected def argType(arg: Arg, formal: Type): Type
@@ -1863,17 +1859,10 @@ trait Applications extends Compatibility {
           else
             alts
 
-        def narrowByTrees(alts: List[TermRef], args: List[Tree], resultType: Type): List[TermRef] = {
-          val alts2 = alts.filterConserve(alt =>
-            isApplicableMethodRef(alt, args, resultType, keepConstraint = false, ArgMatch.SubType)
+        def narrowByTrees(alts: List[TermRef], args: List[Tree], resultType: Type): List[TermRef] =
+          alts.filterConserve(alt =>
+            isApplicableMethodRef(alt, args, resultType, keepConstraint = false, ArgMatch.CompatibleCAP)
           )
-          if (alts2.isEmpty && !ctx.isAfterTyper)
-            alts.filterConserve(alt =>
-              isApplicableMethodRef(alt, args, resultType, keepConstraint = false, ArgMatch.CompatibleCAP)
-            )
-          else
-            alts2
-        }
 
         record("resolveOverloaded.FunProto", alts.length)
         val alts1 = narrowBySize(alts)