JS backend: fix KT-5221 Invalid JS code generated for dec() and inc()

#KT-5221 Fixed

js/js.tests/test/org/jetbrains/k2js/test/semantics/NumberTest.java

@@ -74,6 +74,10 @@ public final class NumberTest extends SingleFileTranslationTest {
         checkFooBoxIsOk();
     }
 
+    public void testNumberIncDec() throws Exception {
+        checkFooBoxIsOk();
+    }
+
     public void testConversionsWithoutTruncation() throws Exception {
         checkFooBoxIsOk();
     }

js/js.translator/src/org/jetbrains/k2js/translate/intrinsic/functions/factories/PrimitiveUnaryOperationFIF.java

@@ -18,9 +18,7 @@ package org.jetbrains.k2js.translate.intrinsic.functions.factories;
 
 import com.google.common.base.Predicate;
 import com.google.common.base.Predicates;
-import com.google.dart.compiler.backend.js.ast.JsExpression;
-import com.google.dart.compiler.backend.js.ast.JsPrefixOperation;
-import com.google.dart.compiler.backend.js.ast.JsUnaryOperator;
+import com.google.dart.compiler.backend.js.ast.*;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 import org.jetbrains.jet.lang.descriptors.FunctionDescriptor;
@@ -61,6 +59,42 @@ public enum PrimitiveUnaryOperationFIF implements FunctionIntrinsicFactory {
     @NotNull
     private static final Predicate<FunctionDescriptor> PATTERN = Predicates.and(PRIMITIVE_UNARY_OPERATION_NAMES, NO_PARAMETERS);
 
+    @NotNull
+    private static final DescriptorPredicate INC_OPERATION_FOR_PRIMITIVE_NUMBER = pattern(PRIMITIVE_NUMBERS, "inc");
+
+    @NotNull
+    private static final DescriptorPredicate DEC_OPERATION_FOR_PRIMITIVE_NUMBER = pattern(PRIMITIVE_NUMBERS, "dec");
+
+    @NotNull
+    private static final FunctionIntrinsic NUMBER_INC_INTRINSIC = new FunctionIntrinsic() {
+        @NotNull
+        @Override
+        public JsExpression apply(
+                @Nullable JsExpression receiver,
+                @NotNull List<JsExpression> arguments,
+                @NotNull TranslationContext context
+        ) {
+            assert receiver != null;
+            assert arguments.size() == 0;
+            return new JsBinaryOperation(JsBinaryOperator.ADD, receiver, context.program().getNumberLiteral(1));
+        }
+    };
+
+    @NotNull
+    private static final FunctionIntrinsic NUMBER_DEC_INTRINSIC = new FunctionIntrinsic() {
+        @NotNull
+        @Override
+        public JsExpression apply(
+                @Nullable JsExpression receiver,
+                @NotNull List<JsExpression> arguments,
+                @NotNull TranslationContext context
+        ) {
+            assert receiver != null;
+            assert arguments.size() == 0;
+            return new JsBinaryOperation(JsBinaryOperator.SUB, receiver, context.program().getNumberLiteral(1));
+        }
+    };
+
     @Nullable
     @Override
     public FunctionIntrinsic getIntrinsic(@NotNull FunctionDescriptor descriptor) {
@@ -68,6 +102,13 @@ public enum PrimitiveUnaryOperationFIF implements FunctionIntrinsicFactory {
             return null;
         }
 
+        if (INC_OPERATION_FOR_PRIMITIVE_NUMBER.apply(descriptor)) {
+            return NUMBER_INC_INTRINSIC;
+        }
+        if (DEC_OPERATION_FOR_PRIMITIVE_NUMBER.apply(descriptor)) {
+            return NUMBER_DEC_INTRINSIC;
+        }
+
         Name name = descriptor.getName();
 
         JsUnaryOperator jsOperator;

js/js.translator/testData/number/cases/numberIncDec.kt

@@ -0,0 +1,16 @@
+package foo
+
+fun box(): String {
+
+    assertEquals(100.inc(), 101)
+    assertEquals(100.dec(), 99)
+
+    var x = 100
+    assertEquals(x.inc(), 101)
+    assertEquals(x, 100)
+
+    assertEquals(x.dec(), 99)
+    assertEquals(x, 100)
+
+    return "OK"
+}