Doesn't support GL_EXT_shader_framebuffer_fetch

```
#version 300 es
#extension GL_EXT_shader_framebuffer_fetch : require

precision mediump float;
uniform sampler2D ContentTexture;
in vec2 vTextureCoordinate0;
inout lowp vec4 fragmentColor;

float blendMultiply(float colorBackdrop, float colorSource)
{
return colorBackdrop * colorSource;
}

float blendScreen(float colorBackdrop, float colorSource)
{
return 1.0 - (1.0 - colorBackdrop) * (1.0 - colorSource);
}

float blendHardLight(float colorBackdrop, float colorSource)
{
if (colorSource <= 0.5)
{
return blendMultiply(colorBackdrop, 2.0 * colorSource);
}
else
{
return blendScreen(colorBackdrop, 2.0 * colorSource - 1.0);
}
}

float blendOverlay(float colorBackdrop, float colorSource)
{
return blendHardLight(colorSource, colorBackdrop);
}

void main()
{
vec4 colorBackdrop = fragmentColor;
vec4 colorSource = texture2D(ContentTexture, vTextureCoordinate0);

colorBackdrop.rgb /= colorBackdrop.a;
colorSource.rgb /= colorSource.a;

fragmentColor = vec4(
blendOverlay(colorBackdrop.r, colorSource.r),
blendOverlay(colorBackdrop.g, colorSource.g),
blendOverlay(colorBackdrop.b, colorSource.b),
colorSource.a);
fragmentColor.rgb *= fragmentColor.a;
}
```
results in
```
ERROR: 0:2: '#extension' : extension not supported: GL_EXT_shader_framebuffer_fetch
ERROR: 0:2: '#extension' : extra tokens -- expected newline
ERROR: 2 compilation errors. No code generated.

ERROR: 0:2: '#extension' : extension not supported: GL_EXT_shader_framebuffer_fetch
ERROR: 0:2: '#extension' : extra tokens -- expected newline
ERROR: 0:2: '' : compilation terminated
ERROR: 3 compilation errors. No code generated.

```
Without the extension declaration the output is this:
```
ERROR: 0:7: '' : cannot use 'inout' at global scope
ERROR: 0:7: '' : compilation terminated
ERROR: 2 compilation errors. No code generated.
```

The same happens on ES2 syntax of the extension, where gl_LastFragData is not recognized.

Use the supplied ES 3 shader and the ES2 form as reproducers, starting with glslang's ESSL extension handling and the reported inout and gl_LastFragData diagnostics. Done means GL_EXT_shader_framebuffer_fetch is recognized in the relevant syntax and the example compiles without those errors.

Written by the indexing model from the issue text.