Adds syntax tests, documentation and changelog entry.

Refines comment for array utility function.

libsolidity/codegen/ArrayUtils.cpp

@@ -840,7 +840,7 @@ void ArrayUtils::popStorageArrayElement(ArrayType const& _type) const
 				let length := and(div(slot_value, 2), 0x1f)
 				if iszero(length) { invalid() }
 
-				// Zero-out the suffix inlcluding the least significant byte.
+				// Zero-out the suffix including the least significant byte.
 				let mask := sub(exp(0x100, sub(33, length)), 1)
 				length := sub(length, 1)
 				slot_value := or(and(not(mask), slot_value), mul(length, 2))

libsolidity/codegen/ArrayUtils.h

@@ -73,7 +73,7 @@ public:
 	/// Stack pre: reference (excludes byte offset)
 	/// Stack post: new_length
 	void incrementDynamicArraySize(ArrayType const& _type) const;
-	/// Decrements the size of a dynamic array by one if length is nonzero. Returns otherwise.
+	/// Decrements the size of a dynamic array by one if length is nonzero. Causes an invalid instruction otherwise.
 	/// Clears the removed data element. In case of a byte array, this might move the data.
 	/// Stack pre: reference
 	/// Stack post: