added constant folding & branch elimination to skslc

tests/SkSLErrorTest.cpp

Index: tests/SkSLErrorTest.cpp
diff --git a/tests/SkSLErrorTest.cpp b/tests/SkSLErrorTest.cpp
index 9e89b71473ab5f3c56aa0238240b2781e232e724..fc20fa2e6d03a79e60f16be096f7716bba90ef09 100644
--- a/tests/SkSLErrorTest.cpp
+++ b/tests/SkSLErrorTest.cpp
@@ -352,3 +352,19 @@ DEF_TEST(SkSLContinueOutsideLoop, r) {
                  "void foo() { for(;;); continue; }",
                  "error: 1: continue statement must be inside a loop\n1 error\n");
 }
+
+DEF_TEST(SkSLStaticIfError, r) {
+    // ensure eliminated branch of static if / ternary is still checked for errors
+    test_failure(r,
+                 "void foo() { if (true); else x = 5; }",
+                 "error: 1: unknown identifier 'x'\n1 error\n");
+    test_failure(r,
+                 "void foo() { if (false) x = 5; }",
+                 "error: 1: unknown identifier 'x'\n1 error\n");
+    test_failure(r,
+                 "void foo() { true ? 5 : x; }",
+                 "error: 1: unknown identifier 'x'\n1 error\n");
+    test_failure(r,
+                 "void foo() { false ? x : 5; }",
+                 "error: 1: unknown identifier 'x'\n1 error\n");
+}