Do not box primitives for 'primitive == object'

NB user-defined 'equals' can violate contract for 'Object#equals', e.g.,
it can be asymmetric.
Thus we can't avoid boxing for 'object == primitive'.

compiler/testData/codegen/bytecodeText/conditions/noBoxingForPrimitiveEqBoxed.kt

@@ -0,0 +1,26 @@
+fun testBoolean1(a: Boolean, b: Boolean?) = a == b
+fun testBoolean2(a: Boolean, b: Boolean?) = a != b
+
+fun testChar1(a: Char, b: Char?) = a == b
+fun testChar2(a: Char, b: Char?) = a != b
+
+fun testByte1(a: Byte, b: Byte?) = a == b
+fun testByte2(a: Byte, b: Byte?) = a != b
+
+fun testShort1(a: Short, b: Short?) = a == b
+fun testShort2(a: Short, b: Short?) = a != b
+
+fun testInt1(a: Int, b: Int?) = a == b
+fun testInt2(a: Int, b: Int?) = a != b
+
+fun testLong1(a: Long, b: Long?) = a == b
+fun testLong2(a: Long, b: Long?) = a != b
+
+// 2 booleanValue
+// 2 charValue
+// 2 byteValue
+// 2 shortValue
+// 2 intValue
+// 2 longValue
+// 0 valueOf
+// 0 areEqual

compiler/testData/codegen/bytecodeText/conditions/noBoxingForPrimitiveEqObject.kt

@@ -0,0 +1,26 @@
+fun testBoolean1(a: Boolean, b: Any?) = a == b
+fun testBoolean2(a: Boolean, b: Any?) = a != b
+
+fun testChar1(a: Char, b: Any?) = a == b
+fun testChar2(a: Char, b: Any?) = a != b
+
+fun testByte1(a: Byte, b: Any?) = a == b
+fun testByte2(a: Byte, b: Any?) = a != b
+
+fun testShort1(a: Short, b: Any?) = a == b
+fun testShort2(a: Short, b: Any?) = a != b
+
+fun testInt1(a: Int, b: Any?) = a == b
+fun testInt2(a: Int, b: Any?) = a != b
+
+fun testLong1(a: Long, b: Any?) = a == b
+fun testLong2(a: Long, b: Any?) = a != b
+
+// 2 booleanValue
+// 2 charValue
+// 2 byteValue
+// 2 shortValue
+// 2 intValue
+// 2 longValue
+// 0 valueOf
+// 0 areEqual