Fix scala#4454 '.' after Number literal is not highlighted

Author: benkobalog

compiler/src/dotty/tools/dotc/printing/SyntaxHighlighting.scala

@@ -129,9 +129,11 @@ object SyntaxHighlighting {
             }
             else if (n.isUpper && keywordStart)
               appendWhile(n, !typeEnders.contains(_), typeDef)
-            else if (numberStart(n))
-              appendWhile(n, { x => x.isDigit || x == '.' || x == '\u0000'}, literal)
-            else
+            else if (numberStart(n)) {
+              def isNumber(c: Char): Boolean =
+                c.isDigit || c == '\u0000' || (c == '.' && remaining.nonEmpty && remaining.head.isDigit)
+              appendWhile(n, isNumber , literal)
+            } else
               newBuf += n; prev = n
           }
         }

compiler/test/dotty/tools/dotc/printing/SyntaxHighlightingTests.scala

@@ -41,6 +41,8 @@ class SyntaxHighlightingTests {
   @Test
   def literals = {
     test("1", "<L|1>")
+    test("1.1", "<L|1.1>")
+    test("1.1.toString", "<L|1.1>.toString")
     // test("1L", "<L|1L>")
   }