Added some tests.

test/libsolidity/syntaxTests/inlineAssembly/invalid/empty_fun_arg.sol

@@ -0,0 +1,13 @@
+contract C {
+  function f() public pure {
+    assembly {
+      function f(a, b) {}
+      f()
+      f(1,)
+      f(,1)
+    }
+  }
+}
+// ----
+// ParserError: (113-114): Literal, identifier or instruction expected.
+// ParserError: (113-114): Expected primary expression.

test/libsolidity/syntaxTests/inlineAssembly/invalid/empty_function_name.sol

@@ -0,0 +1,10 @@
+contract C {
+  function f() public pure {
+    assembly {
+      function (a, b) {}
+    }
+  }
+}
+// ----
+// ParserError: (72-73): Expected identifier but got '('
+// ParserError: (79-80): Expected ';' but got '{'

test/libsolidity/syntaxTests/inlineAssembly/invalid/invalid_number.sol

@@ -0,0 +1,10 @@
+contract C {
+  function f() public pure {
+    assembly {
+      let x := 0100
+    }
+  }
+}
+// ----
+// ParserError: (72-73): Literal, identifier or instruction expected.
+// ParserError: (72-73): Expected primary expression.

test/libsolidity/syntaxTests/inlineAssembly/invalid/missing_variable_in_assign.sol

@@ -0,0 +1,11 @@
+contract C {
+  function f() public pure {
+    assembly {
+      let x := mload(0)
+      := 1
+    }
+  }
+}
+// ----
+// ParserError: (87-88): Literal, identifier or instruction expected.
+// ParserError: (87-88): Expected primary expression.