Add a new test to verify we can reflect invoke toString on a string. …

…The uniqueness here is that java.lang.Object.toString is remapped to a static method.

Fix an issue with how we were invoking remapped methods. The Java reflection information lists the method as an instance method. But it's actually remapped to a static method. Same calling convention, but it turns from a callvirt into a call. This was handled through mw.EmitCallvirtReflect, which got removed in the restriction of ReflectionFactory.
fixes #647

src/IKVM.Java.Tests/java/lang/reflect/StringTests.java

@@ -0,0 +1,14 @@
+package ikvm.tests.java.java.lang.reflect;
+
+import java.lang.reflect.*;
+
+@cli.Microsoft.VisualStudio.TestTools.UnitTesting.TestClassAttribute.Annotation()
+public class StringTests {
+
+    @cli.Microsoft.VisualStudio.TestTools.UnitTesting.TestMethodAttribute.Annotation()
+    public void canInvokeToStringOnString() throws Throwable {
+        String test = "test";
+        test.getClass().getMethod("toString").invoke(test);
+    }
+
+}

src/IKVM.Runtime/Java/Externs/sun/reflect/ReflectionFactory.cs

@@ -729,8 +729,13 @@ internal unsafe FastMethodAccessorImpl(RuntimeJavaMethod mw)
                     // this instance
                     if (s != null)
                     {
-                        // null for static, reference for valuetype/ghost, reference for instance
-                        il.Emit(mw.DeclaringType.IsNonPrimitiveValueType || mw.DeclaringType.IsGhost ? OpCodes.Ldloca : OpCodes.Ldloc, s);
+                        // reference for valuetype/ghost
+                        if (mw.DeclaringType.IsNonPrimitiveValueType || mw.DeclaringType.IsGhost)
+                            il.Emit(OpCodes.Ldloca, s);
+                        else
+                            il.Emit(OpCodes.Ldloc, s);
+
+                        // finished with s
                         il.ReleaseTempLocal(s);
                     }
 
@@ -745,11 +750,11 @@ internal unsafe FastMethodAccessorImpl(RuntimeJavaMethod mw)
                     if (mw.HasCallerID)
                         il.Emit(OpCodes.Ldarg_2);
 
-                    // call method
+                    // static Java method is always a call
                     if (s != null)
-                        il.Emit(OpCodes.Callvirt, mw.GetMethod());
+                        mw.EmitCall(il);
                     else
-                        il.Emit(OpCodes.Call, mw.GetMethod());
+                        mw.EmitCallvirtReflect(il); // reflection virt may be static (remapped) or non-static
 
                     // handle return value
                     mw.ReturnType.EmitConvSignatureTypeToStackType(il);