more skslc hardening

tests/SkSLErrorTest.cpp

 /*
  * Copyright 2016 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkSLCompiler.h"
 
 #include "Test.h"
@@ skipping 121 matching lines @@
     test_failure(r,
                  "void main() { vec4 test = vec2(1).xxxxx; }",
                  "error: 1: too many components in swizzle mask 'xxxxx'\n1 error\n");
 }
 
 DEF_TEST(SkSLSwizzleDuplicateOutput, r) {
     test_failure(r,
                  "void main() { vec4 test = vec4(1); test.xyyz = vec4(1); }",
                  "error: 1: cannot write to the same swizzle field more than once\n1 error\n");
 }
+
 DEF_TEST(SkSLAssignmentTypeMismatch, r) {
     test_failure(r,
                  "void main() { int x = 1.0; }",
                  "error: 1: expected 'int', but found 'float'\n1 error\n");
+    test_failure(r,
+                 "void main() { int x; x = 1.0; }",
+                 "error: 1: type mismatch: '=' cannot operate on 'int', 'float'\n1 error\n");
+    test_success(r,
+                 "void main() { vec3 x = vec3(0); x *= 1.0; }");
+    test_failure(r,
+                 "void main() { ivec3 x = ivec3(0); x *= 1.0; }",
+                 "error: 1: type mismatch: '*=' cannot operate on 'ivec3', 'float'\n1 error\n");
 }
 
 DEF_TEST(SkSLReturnFromVoid, r) {
     test_failure(r,
                  "void main() { return true; }",
                  "error: 1: may not return a value from a void function\n1 error\n");
 }
 
 DEF_TEST(SkSLReturnMissingValue, r) {
     test_failure(r,
@@ skipping 169 matching lines @@
     test_failure(r,
                  "void foo() { while(true) {} if (true) break; }",
                  "error: 1: break statement must be inside a loop\n1 error\n");
 }
 
 DEF_TEST(SkSLContinueOutsideLoop, r) {
     test_failure(r,
                  "void foo() { for(;;); continue; }",
                  "error: 1: continue statement must be inside a loop\n1 error\n");
 }