Prevent JSBody from inlining if its argumet get used more than once

jso/impl/src/main/java/org/teavm/jso/impl/JSBodyAstEmitter.java

@@ -16,7 +16,9 @@
 package org.teavm.jso.impl;
 
 import java.io.IOException;
+import org.mozilla.javascript.Node;
 import org.mozilla.javascript.ast.AstNode;
+import org.mozilla.javascript.ast.Block;
 import org.teavm.codegen.SourceWriter;
 import org.teavm.javascript.Precedence;
 import org.teavm.javascript.spi.GeneratorContext;
@@ -151,7 +153,14 @@ class JSBodyAstEmitter implements JSBodyEmitter {
             astWriter.declareNameEmitter(parameterNames[i], prec -> writer.append(context.getParameterName(index)));
         }
         astWriter.hoist(ast);
-        astWriter.print(ast);
-        writer.softNewLine();
+        if (ast instanceof Block) {
+            for (Node child = ast.getFirstChild(); child != null; child = child.getNext()) {
+                astWriter.print((AstNode) child);
+                writer.softNewLine();
+            }
+        } else {
+            astWriter.print(ast);
+            writer.softNewLine();
+        }
     }
 }

jso/impl/src/main/java/org/teavm/jso/impl/JSBodyInlineUtil.java

@@ -115,7 +115,7 @@ final class JSBodyInlineUtil {
                 Name name = (Name) node;
                 if (!name.isLocalName()) {
                     String id = name.getIdentifier();
-                    usages.put(id, getUsage(id));
+                    usages.put(id, getUsage(id) + 1);
                 }
             }
             return true;

tests/src/test/java/org/teavm/jso/test/ImplementationTest.java

@@ -15,9 +15,10 @@
  */
 package org.teavm.jso.test;
 
-import static org.junit.Assert.*;
+import static org.junit.Assert.assertEquals;
 import org.junit.Test;
 import org.teavm.jso.JSBody;
+import org.teavm.jso.JSObject;
 
 /**
  *
@@ -35,4 +36,27 @@ public class ImplementationTest {
 
     @JSBody(params = { "a", "b" }, script = "return a * b;")
     static final native int mul(int a, int b);
+
+    @Test
+    public void inliningUsageCounterWorksProperly() {
+        ForInliningTest instance = ForInliningTest.create();
+        wrongInlineCandidate(instance.foo());
+        assertEquals(1, instance.counter);
+    }
+
+    @JSBody(params = { "a" }, script = "console.log(a, a);")
+    private static native void wrongInlineCandidate(JSObject a);
+
+    static class ForInliningTest implements JSObject {
+        public int counter = 0;
+
+        public ForInliningTest foo() {
+            ++counter;
+            return this;
+        }
+
+        public static ForInliningTest create() {
+            return new ForInliningTest();
+        }
+    }
 }