Add test for structs/interface-blocks with invalid member names.

Structs already handled this appropriately, but interface blocks did not
guard against naming their member variables built-in type names like
"float" or "bool".

Change-Id: I12ec054b3f158b83e35031449cf2a088ff8d0dc2
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/489596
Auto-Submit: John Stiles <johnstiles@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>

gn/sksl_tests.gni

@@ -66,6 +66,7 @@ sksl_error_tests = [
   "/sksl/errors/InVarWithInitializerExpression.sksl",
   "/sksl/errors/IncompleteExpression.sksl",
   "/sksl/errors/IncompleteFunctionCall.sksl",
+  "/sksl/errors/InterfaceBlockMemberReservedName.sksl",
   "/sksl/errors/InterfaceBlockReservedName.sksl",
   "/sksl/errors/InterfaceBlockScope.sksl",
   "/sksl/errors/InterfaceBlockStorageModifiers.sksl",
@@ -194,6 +195,7 @@ sksl_error_tests = [
   "/sksl/errors/StaticSwitchWithConditionalBreak.sksl",
   "/sksl/errors/StaticSwitchWithConditionalContinue.sksl",
   "/sksl/errors/StaticSwitchWithConditionalReturn.sksl",
+  "/sksl/errors/StructMemberReservedName.sksl",
   "/sksl/errors/StructNameWithoutIdentifier.sksl",
   "/sksl/errors/StructTooDeeplyNested.sksl",
   "/sksl/errors/StructVariableReservedName.sksl",

resources/sksl/errors/InterfaceBlockMemberReservedName.sksl

@@ -0,0 +1,7 @@
+IB {
+    float float;
+} ib;
+
+float4 main() {
+    return ib.float.xxxx;
+}

resources/sksl/errors/StructMemberReservedName.sksl

@@ -0,0 +1,7 @@
+struct S {
+    float float;
+} s;
+
+float4 main() {
+    return s.float.xxxx;
+}

tests/sksl/errors/InterfaceBlockMemberReservedName.glsl

@@ -0,0 +1,7 @@
+
+IB {
+    float float;
+} ib;
+vec4 main() {
+    return vec4(ib.float);
+}

tests/sksl/errors/StructMemberReservedName.glsl

@@ -0,0 +1,4 @@
+### Compilation failed:
+
+error: 2: expected an identifier, but found type 'float'
+1 error