Remove redundant highp fallback that can trigger infinite loop

src/Materials/babylon.effect.ts

@@ -346,16 +346,7 @@
                     this.onCompiled(this);
                 }
             } catch (e) {
-                // Is it a problem with precision?
-                if (e.message.indexOf("highp") !== -1) {
-                    vertexSourceCode = vertexSourceCode.replace("precision highp float", "precision mediump float");
-                    fragmentSourceCode = fragmentSourceCode.replace("precision highp float", "precision mediump float");
-
-                    this._prepareEffect(vertexSourceCode, fragmentSourceCode, attributesNames, defines, fallbacks);
-
-                    return;
-                }
-                // Let's go through fallbacks then
+                // Let's go through fallbacks
                 if (fallbacks && fallbacks.isMoreFallbacks) {
                     Tools.Error("Unable to compile effect with current defines. Trying next fallback.");
                     this._dumpShadersName();