Split TIntermInvariantDeclaration from TIntermAggregate

This change is pure refactoring and doesn't fix bugs related to
invariant declarations. Invariant declarations are supposed to accept
a list of identifiers, but this refactoring keeps the current behavior
of only accepting a single identifier in an invariant declaration.
When the bug will be fixed, the new TIntermInvariantDeclaration class
that now has only a single child node can be changed so that it may
have multiple children.

TIntermAggregate is still used for function calls, function
prototypes and function parameter lists.

BUG=angleproject:1490
TEST=angle_unittests

Change-Id: I3e22092c87e1c06445fd7e123d9922c2fcb59428
Reviewed-on: https://chromium-review.googlesource.com/419415
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Olli Etuaho <oetuaho@nvidia.com>
diff --git a/src/compiler/translator/OutputGLSLBase.cpp b/src/compiler/translator/OutputGLSLBase.cpp
index 775f979..379d6d6 100644
--- a/src/compiler/translator/OutputGLSLBase.cpp
+++ b/src/compiler/translator/OutputGLSLBase.cpp
@@ -959,6 +959,15 @@
     return false;
 }
 
+bool TOutputGLSLBase::visitInvariantDeclaration(Visit visit, TIntermInvariantDeclaration *node)
+{
+    TInfoSinkBase &out = objSink();
+    ASSERT(visit == PreVisit);
+    const TIntermSymbol *symbol = node->getSymbol();
+    out << "invariant " << hashVariableName(symbol->getName());
+    return false;
+}
+
 bool TOutputGLSLBase::visitAggregate(Visit visit, TIntermAggregate *node)
 {
     bool visitChildren       = true;
@@ -1001,18 +1010,6 @@
             out << ")";
             visitChildren = false;
             break;
-        case EOpInvariantDeclaration:
-            // Invariant declaration.
-            ASSERT(visit == PreVisit);
-            {
-                const TIntermSequence *sequence = node->getSequence();
-                ASSERT(sequence && sequence->size() == 1);
-                const TIntermSymbol *symbol = sequence->front()->getAsSymbolNode();
-                ASSERT(symbol);
-                out << "invariant " << hashVariableName(symbol->getName());
-            }
-            visitChildren = false;
-            break;
         case EOpConstructFloat:
         case EOpConstructVec2:
         case EOpConstructVec3: