Clean up function name mangling code

Fix a few incorrect comments about mangled names, and refactor
generating mangled names from function call nodes.

BUG=angleproject:1490
TEST=angle_unittests

Change-Id: I3ee68c4c0982f1a9c28d8e87aafa19f19559bbf8
Reviewed-on: https://chromium-review.googlesource.com/465826
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Commit-Queue: Olli Etuaho <oetuaho@nvidia.com>
diff --git a/src/compiler/translator/ValidateMultiviewWebGL.cpp b/src/compiler/translator/ValidateMultiviewWebGL.cpp
index 79524fc..169a32e 100644
--- a/src/compiler/translator/ValidateMultiviewWebGL.cpp
+++ b/src/compiler/translator/ValidateMultiviewWebGL.cpp
@@ -375,7 +375,8 @@
         }
         else if (!node->isConstructor())
         {
-            TFunction *builtInFunc = mSymbolTable.findBuiltInOp(node, mShaderVersion);
+            TFunction *builtInFunc = static_cast<TFunction *>(
+                mSymbolTable.findBuiltIn(node->getSymbolTableMangledName(), mShaderVersion));
             for (size_t paramIndex = 0u; paramIndex < builtInFunc->getParamCount(); ++paramIndex)
             {
                 TQualifier qualifier = builtInFunc->getParam(paramIndex).type->getQualifier();